diff --git a/src/client/src/tscStream.c b/src/client/src/tscStream.c
index 62443b23ff0032a817fbb187c3958471cb4f2699..2745e4ef87ce2bc4ed7da58f1378c515c036365d 100644
--- a/src/client/src/tscStream.c
+++ b/src/client/src/tscStream.c
@@ -377,7 +377,7 @@ bool sendChildTalbe(TAOS *taos, char *superName, char *tableName, TAOS_FIELD *fi
   }
 
   // init
-  int32_t preLen = strlen(sqlBuf);
+  int32_t preLen = (int32_t)strlen(sqlBuf);
   char *subBuf = sqlBuf + preLen;
   int32_t subLen = bufLen - preLen; 
   sprintf(subBuf, " %s using %s tags(0) values ", dbTable, superName);