diff --git a/src/common/backend/parser/gram.y b/src/common/backend/parser/gram.y
index 3ca55fb97f9a1b74d7887db109604cf937549ba7..96e954cd75152557e65b2fdd71261964b2b8e7d0 100644
--- a/src/common/backend/parser/gram.y
+++ b/src/common/backend/parser/gram.y
@@ -31336,6 +31336,8 @@ static CharsetCollateOptions* MakeCharsetCollateOptions(CharsetCollateOptions *o
 static char* GetValidUserHostId(char* userName, char* hostId)
 {
 	CheckUserHostIsValid();
+	if (strchr(userName,'@'))
+		ereport(ERROR,(errcode(ERRCODE_INVALID_NAME),errmsg("@ can't be allowed in username")));
 	char* userHostId = NULL;
 	if (*hostId == '\'') {
 		userHostId = hostId + 1;
diff --git a/src/test/regress/input/user_host_test.source b/src/test/regress/input/user_host_test.source
index 9b84c25f450292b90744fad9e72d32894a53ace3..12699ddddcb4af0db3c0ef595c40ccfcd6e7f241 100644
--- a/src/test/regress/input/user_host_test.source
+++ b/src/test/regress/input/user_host_test.source
@@ -17,6 +17,7 @@ create user 'test_user_host'@'127.0.%' password 'test123@';
 create user 'test_user_host%' password 'test123@';
 create user 'test_user_host'@'127.0.0.1' password 'test123@';
 set b_compatibility_user_host_auth = on;
+CREATE USER 'da@localhost'@'%' PASSWORD 'test123@';
 create user if not exists 'test_user_host'@'%' password 'test123@';
 alter user 'test_user_host'@'%' with account lock;
 alter user 'test_user_host'@'%' password 'test1234@';
diff --git a/src/test/regress/output/user_host_test.source b/src/test/regress/output/user_host_test.source
index c666fd043645557f843a906a221e0b05d17782d5..a150e999c06ad1a38b92ecc924c28b3cd3342fa1 100644
--- a/src/test/regress/output/user_host_test.source
+++ b/src/test/regress/output/user_host_test.source
@@ -48,6 +48,8 @@ LINE 1: create user 'test_user_host%' password 'test123@';
 create user 'test_user_host'@'127.0.0.1' password 'test123@';
 ERROR:  user@host is only supported in b database when the b_compatibility_user_host_auth is on
 set b_compatibility_user_host_auth = on;
+CREATE USER 'da@localhost'@'%' PASSWORD 'test123@';
+ERROR:  @ can't be allowed in username
 create user if not exists 'test_user_host'@'%' password 'test123@';
 alter user 'test_user_host'@'%' with account lock;
 alter user 'test_user_host'@'%' password 'test1234@';