diff --git a/examples/tencent_firmware_mqtt/tencent_firmware_mqtt.c b/examples/tencent_firmware_mqtt/tencent_firmware_mqtt.c
index a33266e7..f14a9ac9 100644
--- a/examples/tencent_firmware_mqtt/tencent_firmware_mqtt.c
+++ b/examples/tencent_firmware_mqtt/tencent_firmware_mqtt.c
@@ -4,7 +4,7 @@
 
 void mqtt_demo_task(void)
 {
-	char payload[256];
+    char payload[256] = {0};
 
     mqtt_state_t state;
 
@@ -26,54 +26,54 @@ void mqtt_demo_task(void)
     strncpy(dev_info.device_serc, key, DEVICE_SERC_MAX_SIZE);
     tos_tf_module_info_set(&dev_info, TLS_MODE_PSK);
 
-	mqtt_param_t init_params = DEFAULT_MQTT_PARAMS;
-	if (tos_tf_module_mqtt_conn(init_params) != 0) {
-		printf("module mqtt conn fail\n");
-	} else {
-		printf("module mqtt conn success\n");
-	}
+    mqtt_param_t init_params = DEFAULT_MQTT_PARAMS;
+    if (tos_tf_module_mqtt_conn(init_params) != 0) {
+        printf("module mqtt conn fail\n");
+    } else {
+        printf("module mqtt conn success\n");
+    }
 
     if (tos_tf_module_mqtt_state_get(&state) != -1) {
         printf("MQTT: %s\n", state == MQTT_STATE_CONNECTED ? "CONNECTED" : "DISCONNECTED");
     }
 
-	static char topic_name[TOPIC_MAX_SIZE] = {0};
-	int size = snprintf(topic_name, TOPIC_MAX_SIZE, "%s/%s/data", product_id, device_name);
+    static char topic_name[TOPIC_MAX_SIZE] = {0};
+    int size = snprintf(topic_name, TOPIC_MAX_SIZE, "%s/%s/data", product_id, device_name);
 
-	if (size < 0 || size > sizeof(topic_name) - 1) {
-		printf("topic content length not enough! content size:%d  buf size:%d", size, (int)sizeof(topic_name));
-	}
-	if (tos_tf_module_mqtt_sub(topic_name, QOS0) != 0) {
-		printf("module mqtt sub fail\n");
-	} else {
-		printf("module mqtt sub success\n");
-	}
+    if (size < 0 || size > sizeof(topic_name) - 1) {
+        printf("topic content length not enough! content size:%d  buf size:%d", size, (int)sizeof(topic_name));
+    }
+    if (tos_tf_module_mqtt_sub(topic_name, QOS0) != 0) {
+        printf("module mqtt sub fail\n");
+    } else {
+        printf("module mqtt sub success\n");
+    }
 
-	while (1) {
-		HAL_Delay(1000);
+    while (1) {
+        HAL_Delay(1000);
         
         /* use AT+PUB AT command */
-		memset(payload, 0, 256);
+	memset(payload, 0, sizeof(payload));
         strncpy(payload, "{\\\"type\\\":\\\"get\\\"\\, \\\"clientToken\\\":\\\"03UKNYBUZG-0\\\"}", sizeof(payload));
-		printf("message publish: %s\n", payload);
-		if (tos_tf_module_mqtt_pub(topic_name, QOS0, payload) != 0) {
-			printf("module mqtt pub fail\n");
-			break;
-		} else {
-			printf("module mqtt pub success\n");
-		}
+        printf("message publish: %s\n", payload);
+        if (tos_tf_module_mqtt_pub(topic_name, QOS0, payload) != 0) {
+            printf("module mqtt pub fail\n");
+            break;
+        } else {
+            printf("module mqtt pub success\n");
+        }
         
         /* use AT+PUBL AT command */
-        memset(payload, 0, 256);
+        memset(payload, 0, sizeof(payload));
         strncpy(payload, "\"{\\\"type\\\":\\\"get\\\"\\, \\\"clientToken\\\":\\\"03UKNYBUZG-0\\\"}\"", sizeof(payload));
 
-		if (tos_tf_module_mqtt_publ(topic_name, QOS0, payload) != 0) {
-			printf("module mqtt publ fail\n");
-			break;
-		} else {
-			printf("module mqtt publ success\n");
-		}
-	}
+        if (tos_tf_module_mqtt_publ(topic_name, QOS0, payload) != 0) {
+            printf("module mqtt publ fail\n");
+            break;
+        } else {
+            printf("module mqtt publ success\n");
+        }
+    }
 }
 
 void application_entry(void *arg)
@@ -84,4 +84,3 @@ void application_entry(void *arg)
         tos_task_delay(1000);
     }
 }
-