diff --git a/threadfunc/check_thread.cpp b/threadfunc/check_thread.cpp
index e698339..119cafe 100644
--- a/threadfunc/check_thread.cpp
+++ b/threadfunc/check_thread.cpp
@@ -117,6 +117,7 @@ void CheckThread() {
 
         if (1800 == online_check) {
             online_check = 0;
+            JsonData jd;
             int Count = sqlite_db_ctrl::instance().GetTableRows(T_SENSOR_INFO(TNAME), NULL);
             if (Count > 0) {
                 jd.DataNodeStatusCheck();