diff --git a/docs/migration-guide.md b/docs/migration-guide.md
index a3c088f..072147b 100644
--- a/docs/migration-guide.md
+++ b/docs/migration-guide.md
@@ -71,7 +71,7 @@ webclient_close(session);
 
 V2.0.0 版本 GET 请求流如下：
 
-- 创建会话结构体 
+- 创建会话结构体
 - 拼接头部数据（函数拼接方式）
 - 发送 GET 请求头部并接收响应
 - 接收服务器下发数据
@@ -145,7 +145,7 @@ session = webclient_session_create(1024)
 
 webclient_header_fields_add(session, "Content-Length: %s", post_data_sz);
 
-webclient_post(session, URI, post_data, rt_strlen(post_data));
+webclient_post(session, URI, post_data, strlen(post_data));
 
 webclient_close(session);
 ```
diff --git a/docs/user-guide.md b/docs/user-guide.md
index f37b76d..4e204d9 100644
--- a/docs/user-guide.md
+++ b/docs/user-guide.md
@@ -335,7 +335,7 @@ session = webclient_create(1024);
 webclient_header_fields_add(session, "Content-Length: %d\r\n", strlen(post_data));
 webclient_header_fields_add(session, "Content-Type: application/octet-stream\r\n");
 
-if(webclient_post(session, URI, post_data, rt_strlen(post_data)) != 200);
+if(webclient_post(session, URI, post_data, strlen(post_data)) != 200);
 {
     LOG_E("error!");
 }
@@ -354,7 +354,7 @@ char *header = RT_NULL;
 webclient_request_header_add(&header, "Content-Length: %d\r\n", strlen(post_data));
 webclient_request_header_add(&header, "Content-Type: application/octet-stream\r\n");
 
-webclient_request(URI, header, post_data, rt_strlen(post_data), NULL, NULL);
+webclient_request(URI, header, post_data, strlen(post_data), NULL, NULL);
 ```
 
 ## 常见问题
diff --git a/samples/webclient_get_sample.c b/samples/webclient_get_sample.c
index f175381..65d3b04 100644
--- a/samples/webclient_get_sample.c
+++ b/samples/webclient_get_sample.c
@@ -126,7 +126,7 @@ static int webclient_get_smpl(const char *uri)
 
     rt_kprintf("webclient send get request by simplify request interface.\n");
     rt_kprintf("webclient get response data: \n");
-    for (index = 0; index < rt_strlen(response); index++)
+    for (index = 0; index < strlen(response); index++)
     {
         rt_kprintf("%c", response[index]);
     }
@@ -158,7 +158,7 @@ int webclient_get_test(int argc, char **argv)
     }
     else if (argc == 2)
     {
-        if (rt_strcmp(argv[1], "-s") == 0)
+        if (strcmp(argv[1], "-s") == 0)
         {
             uri = web_strdup(GET_LOCAL_URI);
             if(uri == RT_NULL)
@@ -180,7 +180,7 @@ int webclient_get_test(int argc, char **argv)
             webclient_get_comm(uri);
         }
     }
-    else if(argc == 3 && rt_strcmp(argv[1], "-s") == 0)
+    else if(argc == 3 && strcmp(argv[1], "-s") == 0)
     {
         uri = web_strdup(argv[2]);
         if(uri == RT_NULL)
diff --git a/samples/webclient_post_sample.c b/samples/webclient_post_sample.c
index af2b77a..2ffc2f1 100644
--- a/samples/webclient_post_sample.c
+++ b/samples/webclient_post_sample.c
@@ -140,11 +140,11 @@ int webclient_post_test(int argc, char **argv)
             return -RT_ENOMEM;
         }
 
-        webclient_post_comm(uri, (void *)post_data, rt_strlen(post_data));
+        webclient_post_comm(uri, (void *)post_data, strlen(post_data));
     }
     else if (argc == 2)
     {
-        if (rt_strcmp(argv[1], "-s") == 0)
+        if (strcmp(argv[1], "-s") == 0)
         {
             uri = web_strdup(POST_LOCAL_URI);
             if(uri == RT_NULL)
@@ -153,7 +153,7 @@ int webclient_post_test(int argc, char **argv)
                 return -RT_ENOMEM;
             }
 
-            webclient_post_smpl(uri, (void *)post_data, rt_strlen(post_data));
+            webclient_post_smpl(uri, (void *)post_data, strlen(post_data));
         }
         else
         {
@@ -163,10 +163,10 @@ int webclient_post_test(int argc, char **argv)
                 rt_kprintf("no memory for create post request uri buffer.\n");
                 return -RT_ENOMEM;
             }
-            webclient_post_comm(uri, (void *)post_data, rt_strlen(post_data));
+            webclient_post_comm(uri, (void *)post_data, strlen(post_data));
         }
     }
-    else if(argc == 3 && rt_strcmp(argv[1], "-s") == 0)
+    else if(argc == 3 && strcmp(argv[1], "-s") == 0)
     {
         uri = web_strdup(argv[2]);
         if(uri == RT_NULL)
@@ -175,7 +175,7 @@ int webclient_post_test(int argc, char **argv)
             return -RT_ENOMEM;
         }
 
-        webclient_post_smpl(uri, (void *)post_data, rt_strlen(post_data));
+        webclient_post_smpl(uri, (void *)post_data, strlen(post_data));
     }
     else
     {
diff --git a/samples/webclient_shard_download_sample.c b/samples/webclient_shard_download_sample.c
index 8fd8540..55fd4bf 100644
--- a/samples/webclient_shard_download_sample.c
+++ b/samples/webclient_shard_download_sample.c
@@ -71,11 +71,11 @@ int webclient_shard_download_test(int argc, char **argv)
         int index;
         for(index = 1; index < argc; index = index + 2)
         {
-            if(rt_strstr(argv[index], "-u"))
+            if(strstr(argv[index], "-u"))
             {
                 uri = web_strdup(argv[index + 1]);
             }
-            else if(rt_strstr(argv[index], "-l"))
+            else if(strstr(argv[index], "-l"))
             {
                 size = atoi(argv[index + 1]);
             }
diff --git a/src/webclient.c b/src/webclient.c
index 410dd97..4933da9 100644
--- a/src/webclient.c
+++ b/src/webclient.c
@@ -180,7 +180,7 @@ static int webclient_resolve_address(struct webclient_session *session, struct a
 
     /* make sure *res = NULL before getaddrinfo */
     *res = RT_NULL;
-    url_len = rt_strlen(url);
+    url_len = strlen(url);
 
     /* strip protocol(http or https) */
     if (strncmp(url, "http://", 7) == 0)
@@ -189,7 +189,7 @@ static int webclient_resolve_address(struct webclient_session *session, struct a
     }
     else if (strncmp(url, "https://", 8) == 0)
     {
-        rt_strncpy(port_str, "443", 4);
+        strncpy(port_str, "443", 4);
         host_addr = url + 8;
     }
     else
@@ -202,7 +202,7 @@ static int webclient_resolve_address(struct webclient_session *session, struct a
     if (host_addr[0] == '[')
     {
         host_addr += 1;
-        ptr = rt_strstr(host_addr, "]");
+        ptr = strstr(host_addr, "]");
         if (!ptr)
         {
             rc = -WEBCLIENT_ERROR;
@@ -211,21 +211,21 @@ static int webclient_resolve_address(struct webclient_session *session, struct a
         host_addr_len = ptr - host_addr;
     }
 
-    path_ptr = rt_strstr(host_addr, "/");
+    path_ptr = strstr(host_addr, "/");
     *request = path_ptr ? path_ptr : "/";
 
     /* resolve port */
-    port_ptr = rt_strstr(host_addr + host_addr_len, ":");
+    port_ptr = strstr(host_addr + host_addr_len, ":");
     if (port_ptr && (!path_ptr || (port_ptr < path_ptr)))
     {
         if (!path_ptr)
         {
-            rt_strcpy(port_str, port_ptr + 1);
+            strcpy(port_str, port_ptr + 1);
         }
         else
         {
             int port_len = path_ptr - port_ptr - 1;
-            rt_strncpy(port_str, port_ptr + 1, port_len);
+            strncpy(port_str, port_ptr + 1, port_len);
             port_str[port_len] = '\0';
         }
     }
@@ -298,7 +298,7 @@ static int webclient_resolve_address(struct webclient_session *session, struct a
         struct addrinfo hint;
         int ret;
 
-        rt_memset(&hint, 0, sizeof(hint));
+        memset(&hint, 0, sizeof(hint));
         ret = getaddrinfo(session->host, port_str, &hint, res);
         if (ret != 0)
         {
@@ -533,7 +533,7 @@ int webclient_header_fields_add(struct webclient_session *session, const char *f
     RT_ASSERT(session->header->buffer);
 
     va_start(args, fmt);
-    length = rt_vsnprintf(session->header->buffer + session->header->length,
+    length = vsnprintf(session->header->buffer + session->header->length,
             session->header->size - session->header->length, fmt, args);
     va_end(args);
     if (length < 0)
@@ -579,7 +579,7 @@ const char *webclient_header_fields_get(struct webclient_session *session, const
             char *mime_ptr = RT_NULL;
 
             /* jump space */
-            mime_ptr = rt_strstr(resp_buf, ":");
+            mime_ptr = strstr(resp_buf, ":");
             if (mime_ptr != NULL)
             {
                 mime_ptr += 1;
@@ -594,8 +594,8 @@ const char *webclient_header_fields_get(struct webclient_session *session, const
         if (*resp_buf == '\0')
             break;
 
-        resp_buf += rt_strlen(resp_buf) + 1;
-        resp_buf_len += rt_strlen(resp_buf) + 1;
+        resp_buf += strlen(resp_buf) + 1;
+        resp_buf_len += strlen(resp_buf) + 1;
     }
 
     return RT_NULL;
@@ -655,7 +655,7 @@ static int webclient_send_header(struct webclient_session *session, int method)
         if (method != WEBCLIENT_USER_METHOD)
         {
             /* check and add fields header data */
-            if (memcmp(header, "HTTP/1.", rt_strlen("HTTP/1.")))
+            if (memcmp(header, "HTTP/1.", strlen("HTTP/1.")))
             {
                 char *header_buffer = RT_NULL;
                 int length = 0;
@@ -670,13 +670,13 @@ static int webclient_send_header(struct webclient_session *session, int method)
 
                 /* splice http request header data */
                 if (method == WEBCLIENT_GET)
-                    length = rt_snprintf(session->header->buffer, session->header->size, "GET %s HTTP/1.1\r\n%s",
+                    length = snprintf(session->header->buffer, session->header->size, "GET %s HTTP/1.1\r\n%s",
                             session->req_url ? session->req_url : "/", header_buffer);
                 else if (method == WEBCLIENT_POST)
-                    length = rt_snprintf(session->header->buffer, session->header->size, "POST %s HTTP/1.1\r\n%s",
+                    length = snprintf(session->header->buffer, session->header->size, "POST %s HTTP/1.1\r\n%s",
                             session->req_url ? session->req_url : "/", header_buffer);
                 else if (method == WEBCLIENT_HEAD)
-                    length = rt_snprintf(session->header->buffer, session->header->size, "HEAD %s HTTP/1.1\r\n%s",
+                    length = snprintf(session->header->buffer, session->header->size, "HEAD %s HTTP/1.1\r\n%s",
                             session->req_url ? session->req_url : "/", header_buffer);
                 session->header->length = length;
 
@@ -702,7 +702,7 @@ static int webclient_send_header(struct webclient_session *session, int method)
             }
 
             /* header data end */
-            rt_snprintf(session->header->buffer + session->header->length, session->header->size - session->header->length, "\r\n");
+            snprintf(session->header->buffer + session->header->length, session->header->size - session->header->length, "\r\n");
             session->header->length += 2;
 
             /* check header size */
@@ -727,7 +727,7 @@ static int webclient_send_header(struct webclient_session *session, int method)
         int header_line_len;
         LOG_D("request header:");
 
-        for(header_str = session->header->buffer; (header_ptr = rt_strstr(header_str, "\r\n")) != RT_NULL; )
+        for(header_str = session->header->buffer; (header_ptr = strstr(header_str, "\r\n")) != RT_NULL; )
         {
             header_line_len = header_ptr - header_str;
 
@@ -735,7 +735,7 @@ static int webclient_send_header(struct webclient_session *session, int method)
             {
                 LOG_D("%.*s", header_line_len, header_str);
             }
-            header_str = header_ptr + rt_strlen("\r\n");
+            header_str = header_ptr + strlen("\r\n");
         }
 #ifdef WEBCLIENT_DEBUG
         LOG_RAW("\n");
@@ -765,7 +765,7 @@ int webclient_handle_response(struct webclient_session *session)
     RT_ASSERT(session);
 
     /* clean header buffer and size */
-    rt_memset(session->header->buffer, 0x00, session->header->size);
+    memset(session->header->buffer, 0x00, session->header->size);
     session->header->length = 0;
 
     LOG_D("response header:");
@@ -811,11 +811,11 @@ int webclient_handle_response(struct webclient_session *session)
         return -WEBCLIENT_NOMEM;
     }
 
-    if (rt_strstr(mime_ptr, "HTTP/1."))
+    if (strstr(mime_ptr, "HTTP/1."))
     {
         char *ptr = mime_ptr;
 
-        ptr += rt_strlen("HTTP/1.x");
+        ptr += strlen("HTTP/1.x");
 
         while (*ptr && (*ptr == ' ' || *ptr == '\t'))
             ptr++;
@@ -835,7 +835,7 @@ int webclient_handle_response(struct webclient_session *session)
     session->content_remainder = session->content_length ? (size_t) session->content_length : 0xFFFFFFFF;
 
     transfer_encoding = webclient_header_fields_get(session, "Transfer-Encoding");
-    if (transfer_encoding && rt_strcmp(transfer_encoding, "chunked") == 0)
+    if (transfer_encoding && strcmp(transfer_encoding, "chunked") == 0)
     {
         rt_uint16_t len = session->header->size;
         char *line = rt_malloc(len);
@@ -966,7 +966,7 @@ int webclient_get(struct webclient_session *session, const char *URI)
             webclient_clean(session);
             /* clean webclient session header */
             session->header->length = 0;
-            rt_memset(session->header->buffer, 0, session->header->size);
+            memset(session->header->buffer, 0, session->header->size);
 
             rc = webclient_get(session, new_url);
 
@@ -1020,7 +1020,7 @@ int webclient_shard_head_function(struct webclient_session *session, const char
     }
 
     /* clean header buffer and size */
-    rt_memset(session->header->buffer, 0x00, session->header->size);
+    memset(session->header->buffer, 0x00, session->header->size);
     session->header->length = 0;
 
     rc = webclient_send_header(session, WEBCLIENT_HEAD);
@@ -1071,7 +1071,7 @@ int webclient_shard_position_function(struct webclient_session *session, const c
     total_len = start + length;
 
     /* clean header buffer and size */
-    rt_memset(session->header->buffer, 0x00, session->header->size);
+    memset(session->header->buffer, 0x00, session->header->size);
     session->header->length = 0;
 
     for(start_position = end_position; total_len != end_position + 1;)
@@ -1120,7 +1120,7 @@ int webclient_shard_position_function(struct webclient_session *session, const c
                 webclient_clean(session);
                 /* clean webclient session header */
                 session->header->length = 0;
-                rt_memset(session->header->buffer, 0, session->header->size);
+                memset(session->header->buffer, 0, session->header->size);
 
                 rc = webclient_shard_position_function(session, new_url, start, length, mem_size);
 
@@ -1173,7 +1173,7 @@ int webclient_shard_position_function(struct webclient_session *session, const c
         }
 
         /* clean header buffer and size */
-        rt_memset(session->header->buffer, 0x00, session->header->size);
+        memset(session->header->buffer, 0x00, session->header->size);
         session->header->length = 0;
     }
 
@@ -1269,11 +1269,11 @@ static int webclient_next_chunk(struct webclient_session *session)
 
     RT_ASSERT(session);
 
-    rt_memset(line, 0x00, sizeof(line));
+    memset(line, 0x00, sizeof(line));
     length = webclient_read_line(session, line, sizeof(line));
     if (length > 0)
     {
-        if (rt_strcmp(line, "\r") == 0)
+        if (strcmp(line, "\r") == 0)
         {
             length = webclient_read_line(session, line, sizeof(line));
             if (length <= 0)
@@ -1711,8 +1711,8 @@ int webclient_request_header_add(char **request_header, const char *fmt, ...)
     }
 
     va_start(args, fmt);
-    header_length = rt_strlen(header);
-    length = rt_vsnprintf(header + header_length, WEBCLIENT_HEADER_BUFSZ - header_length, fmt, args);
+    header_length = strlen(header);
+    length = vsnprintf(header + header_length, WEBCLIENT_HEADER_BUFSZ - header_length, fmt, args);
     if (length < 0)
     {
         LOG_E("add request header data failed, return length(%d) error.", length);
@@ -1721,7 +1721,7 @@ int webclient_request_header_add(char **request_header, const char *fmt, ...)
     va_end(args);
 
     /* check header size */
-    if (rt_strlen(header) >= WEBCLIENT_HEADER_BUFSZ)
+    if (strlen(header) >= WEBCLIENT_HEADER_BUFSZ)
     {
         LOG_E("not enough request header data size(%d)!", WEBCLIENT_HEADER_BUFSZ);
         return -WEBCLIENT_ERROR;
@@ -1789,9 +1789,9 @@ int webclient_request(const char *URI, const char *header, const void *post_data
             char *header_str, *header_ptr;
             int header_line_length;
 
-            for(header_str = (char *)header; (header_ptr = rt_strstr(header_str, "\r\n")) != RT_NULL; )
+            for(header_str = (char *)header; (header_ptr = strstr(header_str, "\r\n")) != RT_NULL; )
             {
-                header_line_length = header_ptr + rt_strlen("\r\n") - header_str;
+                header_line_length = header_ptr + strlen("\r\n") - header_str;
                 webclient_header_fields_add(session, "%.*s", header_line_length, header_str);
                 header_str += header_line_length;
             }
@@ -1825,20 +1825,20 @@ int webclient_request(const char *URI, const char *header, const void *post_data
             char *header_str, *header_ptr;
             int header_line_length;
 
-            for(header_str = (char *)header; (header_ptr = rt_strstr(header_str, "\r\n")) != RT_NULL; )
+            for(header_str = (char *)header; (header_ptr = strstr(header_str, "\r\n")) != RT_NULL; )
             {
-                header_line_length = header_ptr + rt_strlen("\r\n") - header_str;
+                header_line_length = header_ptr + strlen("\r\n") - header_str;
                 webclient_header_fields_add(session, "%.*s", header_line_length, header_str);
                 header_str += header_line_length;
             }
         }
 
-        if (rt_strstr(session->header->buffer, "Content-Length") == RT_NULL)
+        if (strstr(session->header->buffer, "Content-Length") == RT_NULL)
         {
-            webclient_header_fields_add(session, "Content-Length: %d\r\n", rt_strlen(post_data));
+            webclient_header_fields_add(session, "Content-Length: %d\r\n", strlen(post_data));
         }
 
-        if (rt_strstr(session->header->buffer, "Content-Type") == RT_NULL)
+        if (strstr(session->header->buffer, "Content-Type") == RT_NULL)
         {
             webclient_header_fields_add(session, "Content-Type: application/octet-stream\r\n");
         }
diff --git a/src/webclient_file.c b/src/webclient_file.c
index d5b29a0..2bce5ca 100644
--- a/src/webclient_file.c
+++ b/src/webclient_file.c
@@ -191,28 +191,28 @@ int webclient_post_file(const char* URI, const char* filename,
     header_ptr = header;
 
     /* build boundary */
-    rt_snprintf(boundary, sizeof(boundary), "----------------------------%012d", rt_tick_get());
+    snprintf(boundary, sizeof(boundary), "----------------------------%012d", rt_tick_get());
 
     /* build encapsulated mime_multipart information*/
     buffer_ptr = buffer;
     /* first boundary */
-    buffer_ptr += rt_snprintf((char*) buffer_ptr,
+    buffer_ptr += snprintf((char*) buffer_ptr,
             WEBCLIENT_RESPONSE_BUFSZ - (buffer_ptr - buffer), "--%s\r\n", boundary);
-    buffer_ptr += rt_snprintf((char*) buffer_ptr,
+    buffer_ptr += snprintf((char*) buffer_ptr,
             WEBCLIENT_RESPONSE_BUFSZ - (buffer_ptr - buffer),
             "Content-Disposition: form-data; %s\r\n", form_data);
-    buffer_ptr += rt_snprintf((char*) buffer_ptr,
+    buffer_ptr += snprintf((char*) buffer_ptr,
             WEBCLIENT_RESPONSE_BUFSZ - (buffer_ptr - buffer),
             "Content-Type: application/octet-stream\r\n\r\n");
     /* calculate content-length */
     length += buffer_ptr - buffer;
-    length += rt_strlen(boundary) + 8; /* add the last boundary */
+    length += strlen(boundary) + 8; /* add the last boundary */
 
     /* build header for upload */
-    header_ptr += rt_snprintf(header_ptr,
+    header_ptr += snprintf(header_ptr,
             WEBCLIENT_HEADER_BUFSZ - (header_ptr - header),
             "Content-Length: %d\r\n", length);
-    header_ptr += rt_snprintf(header_ptr,
+    header_ptr += snprintf(header_ptr,
             WEBCLIENT_HEADER_BUFSZ - (header_ptr - header),
             "Content-Type: multipart/form-data; boundary=%s\r\n", boundary);
 
@@ -223,8 +223,8 @@ int webclient_post_file(const char* URI, const char* filename,
         goto __exit;
     }
 
-    rt_strncpy(session->header->buffer, header, rt_strlen(header));
-    session->header->length = rt_strlen(session->header->buffer);
+    strncpy(session->header->buffer, header, strlen(header));
+    session->header->length = strlen(session->header->buffer);
 
     rc = webclient_post(session, URI, NULL, 0);
     if(rc < 0)
@@ -248,8 +248,8 @@ int webclient_post_file(const char* URI, const char* filename,
     }
 
     /* send last boundary */
-    rt_snprintf((char*) buffer, WEBCLIENT_RESPONSE_BUFSZ, "\r\n--%s--\r\n", boundary);
-    webclient_write(session, buffer, rt_strlen(boundary) + 8);
+    snprintf((char*) buffer, WEBCLIENT_RESPONSE_BUFSZ, "\r\n--%s--\r\n", boundary);
+    webclient_write(session, buffer, strlen(boundary) + 8);
 
     extern int webclient_handle_response(struct webclient_session *session);
     if( webclient_handle_response(session) != 200)
@@ -263,7 +263,7 @@ int webclient_post_file(const char* URI, const char* filename,
     {
         int bytes_read = 0;
 
-        rt_memset(buffer, 0x00, WEBCLIENT_RESPONSE_BUFSZ);
+        memset(buffer, 0x00, WEBCLIENT_RESPONSE_BUFSZ);
         do
         {
             bytes_read = webclient_read(session, buffer,