diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index 760a3c4a33..a93ae8e574 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -2573,13 +2573,14 @@ static int32_t translateTimeDiff(SFunctionNode* pFunc, char* pErrBuf, int32_t le
 
   for (int32_t i = 0; i < 2; ++i) {
     uint8_t paraType = getSDataTypeFromNode(nodesListGetNode(pFunc->pParameterList, i))->type;
-    if (!IS_STR_DATA_TYPE(paraType) && !IS_INTEGER_TYPE(paraType) && !IS_TIMESTAMP_TYPE(paraType)) {
+    if (!IS_STR_DATA_TYPE(paraType) && !IS_INTEGER_TYPE(paraType) && !IS_TIMESTAMP_TYPE(paraType) && !IS_NULL_TYPE(paraType)) {
       return invaildFuncParaTypeErrMsg(pErrBuf, len, pFunc->functionName);
     }
   }
-
+  uint8_t para2Type;
   if (3 == numOfParams) {
-    if (!IS_INTEGER_TYPE(getSDataTypeFromNode(nodesListGetNode(pFunc->pParameterList, 2))->type)) {
+    para2Type = getSDataTypeFromNode(nodesListGetNode(pFunc->pParameterList, 2))->type;
+    if (!IS_INTEGER_TYPE(para2Type) && !IS_NULL_TYPE(para2Type)) {
       return invaildFuncParaTypeErrMsg(pErrBuf, len, pFunc->functionName);
     }
   }
@@ -2587,7 +2588,7 @@ static int32_t translateTimeDiff(SFunctionNode* pFunc, char* pErrBuf, int32_t le
   // add database precision as param
   uint8_t dbPrec = pFunc->node.resType.precision;
 
-  if (3 == numOfParams) {
+  if (3 == numOfParams && !IS_NULL_TYPE(para2Type)) {
     int32_t code = validateTimeUnitParam(dbPrec, (SValueNode*)nodesListGetNode(pFunc->pParameterList, 2));
     if (code == TSDB_CODE_FUNC_TIME_UNIT_TOO_SMALL) {
       return buildFuncErrMsg(pErrBuf, len, code,