diff --git a/rtos/code/driver/na51089/source/mcu/sf_battery.c b/rtos/code/driver/na51089/source/mcu/sf_battery.c
index 5aee5cb0f..5308ba129 100755
--- a/rtos/code/driver/na51089/source/mcu/sf_battery.c
+++ b/rtos/code/driver/na51089/source/mcu/sf_battery.c
@@ -931,30 +931,35 @@ THREAD_RETTYPE sf_battery_check_thread(void *arg)
 {
 	THREAD_ENTRY();
     printf("[%s:%d] s\n", __FUNCTION__, __LINE__);
-
-    if(sf_is_battery_low(1, 0) == TRUE)
-    {
-        printf("[%s:%d]power off because low battery\n", __FUNCTION__, __LINE__);
-        //Ux_PostEvent(NVTEVT_SYSTEM_SHUTDOWN, 1, APP_POWER_OFF_BATT_EMPTY); //shutdown start
-        #if (SF_IQ_TEST != ENABLE) && (SF_BATTERY_TEST != ENABLE)
-        sf_set_power_off_flag(APP_POWER_OFF_BATT_EMPTY);
-        flow_preview_set_stop_flag(TRUE);
-        #endif
-        while(1)
-        {
-            vos_util_delay_ms(1000);
-            printf("[%s:%d] cnt power off because low battery\n", __FUNCTION__, __LINE__);
-        }
+    if(sf_is_usb_flag()){
+        printf("[%s:%d]usb power\n", __FUNCTION__, __LINE__);
+        THREAD_RETURN(0);
     }
     else {
-
-        while(sf_while_flag())
+        if(sf_is_battery_low(1, 0) == TRUE)
         {
-            sf_battery_level_polling();
+            printf("[%s:%d]power off because low battery\n", __FUNCTION__, __LINE__);
+            //Ux_PostEvent(NVTEVT_SYSTEM_SHUTDOWN, 1, APP_POWER_OFF_BATT_EMPTY); //shutdown start
+            #if (SF_IQ_TEST != ENABLE) && (SF_BATTERY_TEST != ENABLE)
+            sf_set_power_off_flag(APP_POWER_OFF_BATT_EMPTY);
+            flow_preview_set_stop_flag(TRUE);
+            #endif
+            while(1)
+            {
+                vos_util_delay_ms(1000);
+                printf("[%s:%d] cnt power off because low battery\n", __FUNCTION__, __LINE__);
+            }
         }
+        else {
+
+            while(sf_while_flag())
+            {
+                sf_battery_level_polling();
+            }
+        }
+        printf("[%s:%d] e \n", __FUNCTION__, __LINE__);
+        THREAD_RETURN(0);
     }
-    printf("[%s:%d] e \n", __FUNCTION__, __LINE__);
-	THREAD_RETURN(0);
 }
 
 
@@ -971,7 +976,7 @@ void sf_battery_thread_init(void)
 
 	vos_flag_create(&FLG_ID_SF_BSTTERY, NULL, "FLG_ID_SF_BSTTERY");
 	/*thread creat*/
-   s_handle_batt = vos_task_create(sf_battery_check_thread, NULL, "sf_battery_check_thread", 18, 2048);
+   s_handle_batt = vos_task_create(sf_battery_check_thread, NULL, "sf_battery_check_thread", 18, 4096);
 	vos_task_resume(s_handle_batt);
 	printf("[%s:%d] e\n", __FUNCTION__, __LINE__);
 }