diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index 6165a16711..b2dda963d8 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -817,11 +817,20 @@ static int32_t translateConcatImpl(SFunctionNode* pFunc, char* pErrBuf, int32_t
   int32_t resultBytes = 0;
   int32_t sepBytes = 0;
 
+  //concat_ws separator should be constant string
+  if (hasSep) {
+    SNode* pPara = nodesListGetNode(pFunc->pParameterList, 0);
+    if (nodeType(pPara) != QUERY_NODE_VALUE) {
+      return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_ERROR,
+                             "The first parameter of CONCAT_WS function can only be constant string");
+    }
+  }
+
   /* For concat/concat_ws function, if params have NCHAR type, promote the final result to NCHAR */
   for (int32_t i = 0; i < numOfParams; ++i) {
     SNode*  pPara = nodesListGetNode(pFunc->pParameterList, i);
     uint8_t paraType = ((SExprNode*)pPara)->resType.type;
-    if (!IS_VAR_DATA_TYPE(paraType)) {
+    if (!IS_VAR_DATA_TYPE(paraType) && TSDB_DATA_TYPE_NULL != paraType) {
       return invaildFuncParaTypeErrMsg(pErrBuf, len, pFunc->functionName);
     }
     if (TSDB_DATA_TYPE_NCHAR == paraType) {
diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index 291fbad480..845bdd8064 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -444,7 +444,8 @@ int32_t concatFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
   for (int32_t k = 0; k < numOfRows; ++k) {
     bool hasNull = false;
     for (int32_t i = 0; i < inputNum; ++i) {
-      if (colDataIsNull_s(pInputData[i], k)) {
+      if (colDataIsNull_s(pInputData[i], k) ||
+          GET_PARAM_TYPE(&pInput[i]) == TSDB_DATA_TYPE_NULL) {
         colDataAppendNULL(pOutputData, k);
         hasNull = true;
         break;
@@ -520,7 +521,8 @@ int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
   char *output = outputBuf;
 
   for (int32_t k = 0; k < numOfRows; ++k) {
-    if (colDataIsNull_s(pInputData[0], k)) {
+    if (colDataIsNull_s(pInputData[0], k) ||
+        GET_PARAM_TYPE(&pInput[0]) == TSDB_DATA_TYPE_NULL) {
       colDataAppendNULL(pOutputData, k);
       continue;
     }
@@ -528,7 +530,8 @@ int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
     int16_t dataLen = 0;
     bool hasNull = false;
     for (int32_t i = 1; i < inputNum; ++i) {
-      if (colDataIsNull_s(pInputData[i], k)) {
+      if (colDataIsNull_s(pInputData[i], k) ||
+          GET_PARAM_TYPE(&pInput[i]) == TSDB_DATA_TYPE_NULL) {
         hasNull = true;
         break;
       }