diff --git a/source/libs/executor/src/timewindowoperator.c b/source/libs/executor/src/timewindowoperator.c
index aed4ae9b2668e76d36f759696441dd42996b5a93..e7abf1385151ed404e04b490523e8b857badd5dd 100644
--- a/source/libs/executor/src/timewindowoperator.c
+++ b/source/libs/executor/src/timewindowoperator.c
@@ -2015,7 +2015,11 @@ static void doKeepPrevRows(STimeSliceOperatorInfo* pSliceInfo, const SSDataBlock
 
       pkey->isNull = false;
       char* val = colDataGetData(pColInfoData, rowIndex);
-      memcpy(pkey->pData, val, pkey->bytes);
+      if (!IS_VAR_DATA_TYPE(pkey->type)) {
+        memcpy(pkey->pData, val, pkey->bytes);
+      } else {
+        memcpy(pkey->pData, val, varDataLen(val));
+      }
     }
   }
 
@@ -2033,7 +2037,11 @@ static void doKeepNextRows(STimeSliceOperatorInfo* pSliceInfo, const SSDataBlock
 
       pkey->isNull = false;
       char* val = colDataGetData(pColInfoData, rowIndex);
-      memcpy(pkey->pData, val, pkey->bytes);
+      if (!IS_VAR_DATA_TYPE(pkey->type)) {
+        memcpy(pkey->pData, val, pkey->bytes);
+      } else {
+        memcpy(pkey->pData, val, varDataLen(val));
+      }
     }
   }