diff --git a/APP_Framework/Applications/ota/ota.c b/APP_Framework/Applications/ota/ota.c
index 7f6200f58..52f13bb8a 100644
--- a/APP_Framework/Applications/ota/ota.c
+++ b/APP_Framework/Applications/ota/ota.c
@@ -73,14 +73,16 @@ uint32_t OtaCrc16(uint8_t * data, uint8_t length)
     return reg_crc;
 }
 
-static int SaveAppBin(char* buf, int len)
+static int SaveAppBin(int fd, char* buf, int len)
 {
-    int fd = 0;
-    fd = open( BOARD_APP_NAME, O_RDWR | O_CREAT );
-    lseek(fd, 0, SEEK_END);
+    // int fd = 0;
+    // fd = open( BOARD_APP_NAME, O_RDWR | O_CREAT );
     write(fd, buf, len);
-    close(fd);
+    lseek(fd, len, SEEK_CUR);
+    
+    // close(fd);
 }
+
 static int CrcFileCheck(uint32 crc_check, unsigned long total_len)
 {
     int ret = 0;
@@ -121,6 +123,9 @@ static int OtaDataRecv(struct Adapter* adapter)
     char reply[16] = {0};
     int ret = 0;
     int try_times = 5;
+    int fd = 0;
+
+    fd = open( BOARD_APP_NAME, O_RDWR | O_CREAT | O_TRUNC);
 
     while(1) {
         memset(&recv_msg, 0, sizeof(struct ota_data));
@@ -140,7 +145,7 @@ static int OtaDataRecv(struct Adapter* adapter)
 
             if (recv_msg.frame.crc == OtaCrc16(recv_msg.frame.frame_data,recv_msg.frame.frame_len))
             {
-                SaveAppBin(recv_msg.frame.frame_data, recv_msg.frame.frame_len);
+                SaveAppBin(fd, recv_msg.frame.frame_data, recv_msg.frame.frame_len);
             }  
             else 
             {
@@ -166,6 +171,7 @@ try_again:
             continue;
         }
     }
+    close(fd);
     return ret;
 }
 
@@ -218,6 +224,7 @@ static void *OtaKTaskEntry(void *parameter)
         PrivTaskDelay(3000); /* check ota signal every 3s */
     }
     AdapterDeviceClose(adapter);
+    
 }
 
 void ApplicationOtaTaskInit(void)
diff --git a/APP_Framework/Applications/ota/ota_server.c b/APP_Framework/Applications/ota/ota_server.c
index eb71b1202..84ab322d8 100644
--- a/APP_Framework/Applications/ota/ota_server.c
+++ b/APP_Framework/Applications/ota/ota_server.c
@@ -153,6 +153,10 @@ int OtaFileSend(int fd)
     char * file_buf = NULL;
 
     file_fd = fopen("/tmp/xiuos_app.bin", "r");
+    if (NULL == file_fd){
+        printf("open file failed.\n");
+        return -1;
+    }
 
     while((ch = fgetc(file_fd)) != EOF)
     {
@@ -166,12 +170,13 @@ int OtaFileSend(int fd)
             data.frame.crc = OtaCrc16(data.frame.frame_data, len);
             file_length += len;
         }
+        memcpy(data.frame.frame_data[len], "!@", strlen("!@")); /* add '!@' as ending flag */
         lseek(file_fd, len, SEEK_CUR);
 
 try_again:
         send(fd, &data, sizeof(data), MSG_NOSIGNAL);
         len = recv(fd, buf, sizeof(buf), 0);
-        if(0 == strncmp(buf, "ok", len))
+        if(0 == strncmp(buf, "ok!@", len))
         {
             frame_cnt++;
             continue;
@@ -219,6 +224,7 @@ void* server_thread(void* p)
     int fd = *(int*)p;
     unsigned char buf[32] = { 0 };
     struct ota_data data;
+    int ret = 0;
 
     printf("pthread = %d\n",fd);
 
@@ -231,19 +237,26 @@ void* server_thread(void* p)
 
         send(fd, &data, sizeof(data), MSG_NOSIGNAL);
 
-        len = recv(fd, buf, sizeof(buf),0);
+        len = recv(fd, buf, sizeof(buf), 0);
         if (len <= 0)
         {
             continue;
         }
         else 
         {
-            if(0 == strncmp(buf, "ok", len))
+            if(0 == strncmp(buf, "ok!@", len))
             {
-                OtaFileSend(fd);
+                ret = OtaFileSend(fd);
+                if (ret == 0) {
+                    printf("ota file send successful.\n");
+                    break;
+                } else { /* ota failed then restart the ota process */
+                    continue;
+                }
             }
         }
     }
+    close(fd);
 }
 
 void server(void)
diff --git a/APP_Framework/Framework/connection/4g/adapter_4g.c b/APP_Framework/Framework/connection/4g/adapter_4g.c
index 00bf150db..3a3b40dbe 100644
--- a/APP_Framework/Framework/connection/4g/adapter_4g.c
+++ b/APP_Framework/Framework/connection/4g/adapter_4g.c
@@ -51,7 +51,7 @@ int Adapter4GInit(void)
 
     struct Adapter *adapter = PrivMalloc(sizeof(struct Adapter));
     if (!adapter) {
-        free(adapter);
+        Privfree(adapter);
         return -1;
     }
 
@@ -60,7 +60,7 @@ int Adapter4GInit(void)
     ret = Adapter4GRegister(adapter);
     if (ret < 0) {
         printf("Adapter4GInit register 4G adapter error\n");
-        free(adapter);
+        Privfree(adapter);
         return -1;
     }
 
@@ -68,7 +68,7 @@ int Adapter4GInit(void)
     AdapterProductInfoType product_info = Ec200tAttach(adapter);
     if (!product_info) {
         printf("Adapter4GInit ec200t attach error\n");
-        free(adapter);
+        Privfree(adapter);
         return -1;
     }
 
@@ -112,4 +112,4 @@ int Adapter4GTest(void)
 
     return 0;    
 }
-SHELL_EXPORT_CMD(SHELL_CMD_PERMISSION(0)|SHELL_CMD_TYPE(SHELL_TYPE_CMD_FUNC)|SHELL_CMD_PARAM_NUM(0)|SHELL_CMD_DISABLE_RETURN, Adapter4GTest, Adapter4GTest, show adapter 4G information);
+// SHELL_EXPORT_CMD(SHELL_CMD_PERMISSION(0)|SHELL_CMD_TYPE(SHELL_TYPE_CMD_FUNC)|SHELL_CMD_PARAM_NUM(0)|SHELL_CMD_DISABLE_RETURN, Adapter4GTest, Adapter4GTest, show adapter 4G information);