diff --git a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h
index 260e653..d89bd16 100644
--- a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h
+++ b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/include/iot_mqtt_srv.h
@@ -21,8 +21,8 @@
 #define IOT_MQTT_RECONNECT_MIN_MS  5000      // 最小重连间隔
 #define IOT_MQTT_RECONNECT_MAX_MS  60000     // 最大重连间隔 (指数退避上限)
 #define IOT_MQTT_HEARTBEAT_MS      60000     // 心跳上报周期 (60s)
-#define IOT_MQTT_RECV_BUF_LEN      2048      // 接收缓冲区
-#define IOT_MQTT_SEND_BUF_LEN      2048      // 发送缓冲区
+#define IOT_MQTT_RECV_BUF_LEN      1024      // 接收缓冲区 (单次交互 ≤1024)
+#define IOT_MQTT_SEND_BUF_LEN      1024      // 发送缓冲区 (单次交互 ≤1024)
 #define IOT_MQTT_TOPIC_MAX_LEN     128       // Topic 最大长度
 
 /*===========================================================================
diff --git a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c
index 8c30c67..2a6d65a 100644
--- a/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c
+++ b/vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/iot_mqtt_srv.c
@@ -168,7 +168,7 @@ static int iot_mqtt_publish(const char *topic, const char *payload,
 
 /* 处理一条收到的 MQTT PUBLISH 消息 */
 static void iot_handle_publish(const char *topic, uint8_t *payload, int payload_len) {
-    char json[IOT_MQTT_RECV_BUF_LEN];
+    static char json[IOT_MQTT_RECV_BUF_LEN];  // static: 避免 1KB 栈开销
     int copy_len = payload_len < (int)sizeof(json) - 1 ? payload_len : (int)sizeof(json) - 1;
     memcpy(json, payload, copy_len);
     json[copy_len] = '\0';
@@ -392,7 +392,7 @@ void iot_mqtt_publish_sensor(void) {
     }
 
     /* 构建 loop_data JSON */
-    static char data_json[2048];   // static: 避免 2KB 栈溢出
+    static char data_json[IOT_MQTT_SEND_BUF_LEN];   // static: 避免栈溢出
     char *p = data_json;
     int remaining = sizeof(data_json);
     int written;