diff --git a/cmd/explaintest/r/new_character_set_builtin.result b/cmd/explaintest/r/new_character_set_builtin.result
index a13ddf6722584..bb4e9feaae201 100644
--- a/cmd/explaintest/r/new_character_set_builtin.result
+++ b/cmd/explaintest/r/new_character_set_builtin.result
@@ -141,3 +141,14 @@ select md5(a), md5(b), md5(c) from t;
 md5(a)	md5(b)	md5(c)
 8093a32450075324682d01456d6e3919	a45d4af7b243e7f393fa09bed72ac73e	aae0117857fe54811a5239275dd81133
 set @@tidb_enable_vectorized_expression = false;
+drop table if exists t;
+create table t (a char(20) charset utf8mb4, b char(20) charset gbk, c binary(20));
+insert into t values ('一二三', '一二三', '一二三');
+select decode(encode(a,"monty"),"monty") = a, md5(decode(encode(b,"monty"),"monty")) = md5(b), decode(encode(c,"monty"),"monty") = c from t;
+decode(encode(a,"monty"),"monty") = a	md5(decode(encode(b,"monty"),"monty")) = md5(b)	decode(encode(c,"monty"),"monty") = c
+1	1	1
+set @@tidb_enable_vectorized_expression = true;
+select decode(encode(a,"monty"),"monty") = a, md5(decode(encode(b,"monty"),"monty")) = md5(b), decode(encode(c,"monty"),"monty") = c from t;
+decode(encode(a,"monty"),"monty") = a	md5(decode(encode(b,"monty"),"monty")) = md5(b)	decode(encode(c,"monty"),"monty") = c
+1	1	1
+set @@tidb_enable_vectorized_expression = false;
diff --git a/cmd/explaintest/t/new_character_set_builtin.test b/cmd/explaintest/t/new_character_set_builtin.test
index 04ee066344d11..d5d0bcc9a14f5 100644
--- a/cmd/explaintest/t/new_character_set_builtin.test
+++ b/cmd/explaintest/t/new_character_set_builtin.test
@@ -66,3 +66,12 @@ select md5(a), md5(b), md5(c) from t;
 set @@tidb_enable_vectorized_expression = true;
 select md5(a), md5(b), md5(c) from t;
 set @@tidb_enable_vectorized_expression = false;
+
+-- test for builtin function decode()/encode()
+drop table if exists t;
+create table t (a char(20) charset utf8mb4, b char(20) charset gbk, c binary(20));
+insert into t values ('一二三', '一二三', '一二三');
+select decode(encode(a,"monty"),"monty") = a, md5(decode(encode(b,"monty"),"monty")) = md5(b), decode(encode(c,"monty"),"monty") = c from t;
+set @@tidb_enable_vectorized_expression = true;
+select decode(encode(a,"monty"),"monty") = a, md5(decode(encode(b,"monty"),"monty")) = md5(b), decode(encode(c,"monty"),"monty") = c from t;
+set @@tidb_enable_vectorized_expression = false;
diff --git a/expression/builtin_encryption.go b/expression/builtin_encryption.go
index 3267033421071..47a1d717b5f37 100644
--- a/expression/builtin_encryption.go
+++ b/expression/builtin_encryption.go
@@ -407,11 +407,21 @@ func (b *builtinDecodeSig) evalString(row chunk.Row) (string, bool, error) {
 	if isNull || err != nil {
 		return "", true, err
 	}
+	dataTp := b.args[0].GetType()
+	dataStr, err = charset.NewEncoding(dataTp.Charset).EncodeString(dataStr)
+	if err != nil {
+		return "", false, err
+	}
 
 	passwordStr, isNull, err := b.args[1].EvalString(b.ctx, row)
 	if isNull || err != nil {
 		return "", true, err
 	}
+	passwordTp := b.args[1].GetType()
+	passwordStr, err = charset.NewEncoding(passwordTp.Charset).EncodeString(passwordStr)
+	if err != nil {
+		return "", false, err
+	}
 
 	decodeStr, err := encrypt.SQLDecode(dataStr, passwordStr)
 	return decodeStr, false, err
@@ -470,11 +480,21 @@ func (b *builtinEncodeSig) evalString(row chunk.Row) (string, bool, error) {
 	if isNull || err != nil {
 		return "", true, err
 	}
+	decodeTp := b.args[0].GetType()
+	decodeStr, err = charset.NewEncoding(decodeTp.Charset).EncodeString(decodeStr)
+	if err != nil {
+		return "", false, err
+	}
 
 	passwordStr, isNull, err := b.args[1].EvalString(b.ctx, row)
 	if isNull || err != nil {
 		return "", true, err
 	}
+	passwordTp := b.args[1].GetType()
+	passwordStr, err = charset.NewEncoding(passwordTp.Charset).EncodeString(passwordStr)
+	if err != nil {
+		return "", false, err
+	}
 
 	dataStr, err := encrypt.SQLEncode(decodeStr, passwordStr)
 	return dataStr, false, err
diff --git a/expression/builtin_encryption_test.go b/expression/builtin_encryption_test.go
index 505729a462d09..1224cec517fce 100644
--- a/expression/builtin_encryption_test.go
+++ b/expression/builtin_encryption_test.go
@@ -33,37 +33,44 @@ import (
 )
 
 var cryptTests = []struct {
+	chs      string
 	origin   interface{}
 	password interface{}
 	crypt    interface{}
 }{
-	{"", "", ""},
-	{"pingcap", "1234567890123456", "2C35B5A4ADF391"},
-	{"pingcap", "asdfjasfwefjfjkj", "351CC412605905"},
-	{"pingcap123", "123456789012345678901234", "7698723DC6DFE7724221"},
-	{"pingcap#%$%^", "*^%YTu1234567", "8634B9C55FF55E5B6328F449"},
-	{"pingcap", "", "4A77B524BD2C5C"},
-	{"分布式データベース", "pass1234@#$%%^^&", "80CADC8D328B3026D04FB285F36FED04BBCA0CC685BF78B1E687CE"},
-	{"分布式データベース", "分布式7782734adgwy1242", "0E24CFEF272EE32B6E0BFBDB89F29FB43B4B30DAA95C3F914444BC"},
-	{"pingcap", "密匙", "CE5C02A5010010"},
-	{"pingcap数据库", "数据库passwd12345667", "36D5F90D3834E30E396BE3226E3B4ED3"},
-	{"数据库5667", 123.435, "B22196D0569386237AE12F8AAB"},
-	{nil, "数据库passwd12345667", nil},
+	{mysql.DefaultCollationName, "", "", ""},
+	{mysql.DefaultCollationName, "pingcap", "1234567890123456", "2C35B5A4ADF391"},
+	{mysql.DefaultCollationName, "pingcap", "asdfjasfwefjfjkj", "351CC412605905"},
+	{mysql.DefaultCollationName, "pingcap123", "123456789012345678901234", "7698723DC6DFE7724221"},
+	{mysql.DefaultCollationName, "pingcap#%$%^", "*^%YTu1234567", "8634B9C55FF55E5B6328F449"},
+	{mysql.DefaultCollationName, "pingcap", "", "4A77B524BD2C5C"},
+	{mysql.DefaultCollationName, "分布式データベース", "pass1234@#$%%^^&", "80CADC8D328B3026D04FB285F36FED04BBCA0CC685BF78B1E687CE"},
+	{mysql.DefaultCollationName, "分布式データベース", "分布式7782734adgwy1242", "0E24CFEF272EE32B6E0BFBDB89F29FB43B4B30DAA95C3F914444BC"},
+	{mysql.DefaultCollationName, "pingcap", "密匙", "CE5C02A5010010"},
+	{"gbk", "pingcap", "密匙", "E407AC6F691ADE"},
+	{mysql.DefaultCollationName, "pingcap数据库", "数据库passwd12345667", "36D5F90D3834E30E396BE3226E3B4ED3"},
+	{"gbk", "pingcap数据库", "数据库passwd12345667", "B4BDBD6EC8346379F42836E2E0"},
+	{mysql.DefaultCollationName, "数据库5667", 123.435, "B22196D0569386237AE12F8AAB"},
+	{"gbk", "数据库5667", 123.435, "79E22979BD860EF58229"},
+	{mysql.DefaultCollationName, nil, "数据库passwd12345667", nil},
 }
 
 func TestSQLDecode(t *testing.T) {
 	t.Parallel()
 	ctx := createContext(t)
-	fc := funcs[ast.Decode]
 	for _, tt := range cryptTests {
-		str := types.NewDatum(tt.origin)
-		password := types.NewDatum(tt.password)
-
-		f, err := fc.getFunction(ctx, datumsToConstants([]types.Datum{str, password}))
+		err := ctx.GetSessionVars().SetSystemVar(variable.CharacterSetConnection, tt.chs)
 		require.NoError(t, err)
-		crypt, err := evalBuiltinFunc(f, chunk.Row{})
+		err = ctx.GetSessionVars().SetSystemVar(variable.CollationConnection, tt.chs)
 		require.NoError(t, err)
-		require.Equal(t, types.NewDatum(tt.crypt), toHex(crypt))
+		f, err := newFunctionForTest(ctx, ast.Decode, primitiveValsToConstants(ctx, []interface{}{tt.origin, tt.password})...)
+		require.NoError(t, err)
+		d, err := f.Eval(chunk.Row{})
+		require.NoError(t, err)
+		if !d.IsNull() {
+			d = toHex(d)
+		}
+		require.Equal(t, types.NewDatum(tt.crypt), d)
 	}
 	testNullInput(t, ctx, ast.Decode)
 }
@@ -71,18 +78,29 @@ func TestSQLDecode(t *testing.T) {
 func TestSQLEncode(t *testing.T) {
 	t.Parallel()
 	ctx := createContext(t)
-
-	fc := funcs[ast.Encode]
 	for _, test := range cryptTests {
-		password := types.NewDatum(test.password)
-		cryptStr := fromHex(test.crypt)
-
-		f, err := fc.getFunction(ctx, datumsToConstants([]types.Datum{cryptStr, password}))
+		err := ctx.GetSessionVars().SetSystemVar(variable.CharacterSetConnection, test.chs)
 		require.NoError(t, err)
-		str, err := evalBuiltinFunc(f, chunk.Row{})
-
+		err = ctx.GetSessionVars().SetSystemVar(variable.CollationConnection, test.chs)
+		require.NoError(t, err)
+		var h []byte
+		if test.crypt != nil {
+			h, _ = hex.DecodeString(test.crypt.(string))
+		} else {
+			h = nil
+		}
+		f, err := newFunctionForTest(ctx, ast.Encode, primitiveValsToConstants(ctx, []interface{}{h, test.password})...)
 		require.NoError(t, err)
-		require.Equal(t, types.NewDatum(test.origin), str)
+		d, err := f.Eval(chunk.Row{})
+		require.NoError(t, err)
+		if test.origin != nil {
+			result, err := charset.NewEncoding(test.chs).EncodeString(test.origin.(string))
+			require.NoError(t, err)
+			require.Equal(t, types.NewCollationStringDatum(result, test.chs, 1), d)
+		} else {
+			result := types.NewDatum(test.origin)
+			require.Equal(t, result.GetBytes(), d.GetBytes())
+		}
 	}
 	testNullInput(t, ctx, ast.Encode)
 }
diff --git a/expression/builtin_encryption_vec.go b/expression/builtin_encryption_vec.go
index b7d9cfc785294..b9c0ff43ddd1e 100644
--- a/expression/builtin_encryption_vec.go
+++ b/expression/builtin_encryption_vec.go
@@ -212,6 +212,9 @@ func (b *builtinDecodeSig) vecEvalString(input *chunk.Chunk, result *chunk.Colum
 	if err := b.args[0].VecEvalString(b.ctx, input, buf); err != nil {
 		return err
 	}
+	dataTp := b.args[0].GetType()
+	dataEnc := charset.NewEncoding(dataTp.Charset)
+
 	buf1, err1 := b.bufAllocator.get()
 	if err1 != nil {
 		return err1
@@ -220,14 +223,22 @@ func (b *builtinDecodeSig) vecEvalString(input *chunk.Chunk, result *chunk.Colum
 	if err := b.args[1].VecEvalString(b.ctx, input, buf1); err != nil {
 		return err
 	}
+	passwordTp := b.args[1].GetType()
+	passwordEnc := charset.NewEncoding(passwordTp.Charset)
 	result.ReserveString(n)
 	for i := 0; i < n; i++ {
 		if buf.IsNull(i) || buf1.IsNull(i) {
 			result.AppendNull()
 			continue
 		}
-		dataStr := buf.GetString(i)
-		passwordStr := buf1.GetString(i)
+		dataStr, err := dataEnc.EncodeString(buf.GetString(i))
+		if err != nil {
+			return err
+		}
+		passwordStr, err := passwordEnc.EncodeString(buf1.GetString(i))
+		if err != nil {
+			return err
+		}
 		decodeStr, err := encrypt.SQLDecode(dataStr, passwordStr)
 		if err != nil {
 			return err
@@ -255,18 +266,29 @@ func (b *builtinEncodeSig) vecEvalString(input *chunk.Chunk, result *chunk.Colum
 	if err1 != nil {
 		return err1
 	}
+	dataTp := b.args[0].GetType()
+	dataEnc := charset.NewEncoding(dataTp.Charset)
 	defer b.bufAllocator.put(buf1)
 	if err := b.args[1].VecEvalString(b.ctx, input, buf1); err != nil {
 		return err
 	}
+	passwordTp := b.args[1].GetType()
+	passwordEnc := charset.NewEncoding(passwordTp.Charset)
 	result.ReserveString(n)
 	for i := 0; i < n; i++ {
 		if buf.IsNull(i) || buf1.IsNull(i) {
 			result.AppendNull()
 			continue
 		}
-		decodeStr := buf.GetString(i)
-		passwordStr := buf1.GetString(i)
+
+		decodeStr, err := dataEnc.EncodeString(buf.GetString(i))
+		if err != nil {
+			return err
+		}
+		passwordStr, err := passwordEnc.EncodeString(buf1.GetString(i))
+		if err != nil {
+			return err
+		}
 		dataStr, err := encrypt.SQLEncode(decodeStr, passwordStr)
 		if err != nil {
 			return err