diff --git a/include/util/taoserror.h b/include/util/taoserror.h
index c5b477343db6cd4ffe299db6913a6a3298d199b7..6c5e006671541dec1ab2059d90b9471358e6df80 100644
--- a/include/util/taoserror.h
+++ b/include/util/taoserror.h
@@ -617,6 +617,7 @@ int32_t* taosGetErrno();
 #define TSDB_CODE_FUNC_FUNTION_ERROR            TAOS_DEF_ERROR_CODE(0, 0x2800)
 #define TSDB_CODE_FUNC_FUNTION_PARA_NUM         TAOS_DEF_ERROR_CODE(0, 0x2801)
 #define TSDB_CODE_FUNC_FUNTION_PARA_TYPE        TAOS_DEF_ERROR_CODE(0, 0x2802)
+#define TSDB_CODE_FUNC_FUNTION_PARA_VALUE       TAOS_DEF_ERROR_CODE(0, 0x2803)
 
 #ifdef __cplusplus
 }
diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index 78dec26be59b067ef7fddd66b98b12b01e1a33e4..5ba0cee53eddb83d778fbe7961ffe3f8ca587c52 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -28,13 +28,17 @@ static int32_t buildFuncErrMsg(char* pErrBuf, int32_t len, int32_t errCode, cons
 }
 
 static int32_t invaildFuncParaNumErrMsg(char* pErrBuf, int32_t len, const char* pFuncName) {
-  return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_PARA_NUM, "Invalid number of arguments : %s", pFuncName);
+  return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_PARA_NUM, "Invalid number of parameters : %s", pFuncName);
 }
 
 static int32_t invaildFuncParaTypeErrMsg(char* pErrBuf, int32_t len, const char* pFuncName) {
   return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_PARA_TYPE, "Inconsistent datatypes : %s", pFuncName);
 }
 
+static int32_t invaildFuncParaValueErrMsg(char* pErrBuf, int32_t len, const char* pFuncName) {
+  return buildFuncErrMsg(pErrBuf, len, TSDB_CODE_FUNC_FUNTION_PARA_VALUE, "Invalid parameter value : %s", pFuncName);
+}
+
 // There is only one parameter of numeric type, and the return type is parameter type
 static int32_t translateInOutNum(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
   if (1 != LIST_LENGTH(pFunc->pParameterList)) {
@@ -317,10 +321,15 @@ static int32_t translateCast(SFunctionNode* pFunc, char* pErrBuf, int32_t len) {
   uint8_t para1Type = ((SExprNode*)nodesListGetNode(pFunc->pParameterList, 0))->resType.type;
   // The function return type has been set during syntax parsing
   uint8_t para2Type = pFunc->node.resType.type;
-  if ((TSDB_DATA_TYPE_JSON == para1Type || TSDB_DATA_TYPE_BLOB == para1Type || TSDB_DATA_TYPE_MEDIUMBLOB == para1Type) ||
-      (TSDB_DATA_TYPE_JSON == para2Type || TSDB_DATA_TYPE_BLOB == para2Type || TSDB_DATA_TYPE_MEDIUMBLOB == para2Type)) {
+  if (para2Type != TSDB_DATA_TYPE_BIGINT && para2Type != TSDB_DATA_TYPE_UBIGINT &&
+      para2Type != TSDB_DATA_TYPE_VARCHAR && para2Type != TSDB_DATA_TYPE_NCHAR &&
+      para2Type != TSDB_DATA_TYPE_TIMESTAMP) {
     return invaildFuncParaTypeErrMsg(pErrBuf, len, pFunc->functionName);
   }
+  int32_t para2Bytes = pFunc->node.resType.bytes;
+  if (para2Bytes < 0) { //negative value or overflow
+    return invaildFuncParaValueErrMsg(pErrBuf, len, pFunc->functionName);
+  }
   return TSDB_CODE_SUCCESS;
 }
 
diff --git a/source/libs/scalar/src/scalar.c b/source/libs/scalar/src/scalar.c
index 0432ae1df877fcc35ece5aac538a2f0b80d91b8f..e6de165ab5c3a36151c0a76d7cdff5e75dbb5c93 100644
--- a/source/libs/scalar/src/scalar.c
+++ b/source/libs/scalar/src/scalar.c
@@ -444,6 +444,9 @@ EDealRes sclRewriteFunction(SNode** pNode, SScalarCtx *ctx) {
     res->node.resType.type = TSDB_DATA_TYPE_NULL;
   } else {
     res->node.resType = node->node.resType;
+    if (res->node.resType.type == TSDB_DATA_TYPE_NCHAR) {
+      res->node.resType.bytes *= TSDB_NCHAR_SIZE;
+    }
     int32_t type = output.columnData->info.type;
     if (IS_VAR_DATA_TYPE(type)) {
       res->datum.p = output.columnData->pData;
diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index e7ff0bde918ac05094edb2d151c755b609ad5425..995d38e9b7ce27014a03dd3c4ccf1b3477fc0dcc 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -646,13 +646,13 @@ int32_t substrFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
 int32_t castFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput) {
   int16_t inputType  = pInput[0].columnData->info.type;
   int16_t outputType = pOutput[0].columnData->info.type;
-  if (outputType != TSDB_DATA_TYPE_BIGINT && outputType != TSDB_DATA_TYPE_UBIGINT &&
-      outputType != TSDB_DATA_TYPE_VARCHAR && outputType != TSDB_DATA_TYPE_NCHAR &&
-      outputType != TSDB_DATA_TYPE_TIMESTAMP) {
-    return TSDB_CODE_FAILED;
-  }
   int64_t outputLen = pOutput[0].columnData->info.bytes;
 
+  if (IS_VAR_DATA_TYPE(outputType)) {
+    int32_t factor = (TSDB_DATA_TYPE_NCHAR == outputType) ? TSDB_NCHAR_SIZE : 1;
+    outputLen = outputLen * factor + VARSTR_HEADER_SIZE;
+  }
+
   char *input = NULL;
   char *outputBuf = taosMemoryCalloc(outputLen * pInput[0].numOfRows, 1);
   char *output = outputBuf;
@@ -723,7 +723,7 @@ int32_t castFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutp
         } else if (inputType == TSDB_DATA_TYPE_BINARY) {
           int32_t len = sprintf(varDataVal(output), "%.*s", (int32_t)(outputLen - VARSTR_HEADER_SIZE), varDataVal(input));
           varDataSetLen(output, len);
-        } else if (inputType == TSDB_DATA_TYPE_BINARY || inputType == TSDB_DATA_TYPE_NCHAR) {
+        } else if (inputType == TSDB_DATA_TYPE_NCHAR) {
           //not support
           return TSDB_CODE_FAILED;
         } else {