diff --git a/fe/src/main/cup/sql_parser.cup b/fe/src/main/cup/sql_parser.cup
index 0f6740d39ae169..5c66fe3f6cab7b 100644
--- a/fe/src/main/cup/sql_parser.cup
+++ b/fe/src/main/cup/sql_parser.cup
@@ -4369,6 +4369,8 @@ keyword ::=
     {: RESULT = id; :}
     | KW_FORMAT:id
     {: RESULT = id; :}
+    | KW_HLL_UNION:id
+    {: RESULT = id; :}
     | KW_PATH:id
     {: RESULT = id; :}
     | KW_FUNCTION:id
diff --git a/fe/src/main/java/org/apache/doris/catalog/FunctionSet.java b/fe/src/main/java/org/apache/doris/catalog/FunctionSet.java
index 256a461921f354..4f9a0c75da7468 100644
--- a/fe/src/main/java/org/apache/doris/catalog/FunctionSet.java
+++ b/fe/src/main/java/org/apache/doris/catalog/FunctionSet.java
@@ -1026,7 +1026,17 @@ private void initAggregateBuiltins() {
                     "_ZN5doris12HllFunctions12hll_finalizeEPN9doris_udf15FunctionContextERKNS1_9StringValE",
                     true, true, true));
 
-            // HLL_RAW_AGG
+            // HLL_UNION
+            addBuiltin(AggregateFunction.createBuiltin("hll_union",
+                    Lists.newArrayList(t), Type.HLL, Type.HLL,
+                    "_ZN5doris12HllFunctions8hll_initEPN9doris_udf15FunctionContextEPNS1_9StringValE",
+                    "_ZN5doris12HllFunctions9hll_mergeEPN9doris_udf15FunctionContextERKNS1_9StringValEPS4_",
+                    "_ZN5doris12HllFunctions9hll_mergeEPN9doris_udf15FunctionContextERKNS1_9StringValEPS4_",
+                    "_ZN5doris12HllFunctions13hll_serializeEPN9doris_udf15FunctionContextERKNS1_9StringValE",
+                    "_ZN5doris12HllFunctions13hll_serializeEPN9doris_udf15FunctionContextERKNS1_9StringValE",
+                    true, false, true));
+
+            // HLL_RAW_AGG is alias of HLL_UNION
             addBuiltin(AggregateFunction.createBuiltin("hll_raw_agg",
                     Lists.newArrayList(t), Type.HLL, Type.HLL,
                     "_ZN5doris12HllFunctions8hll_initEPN9doris_udf15FunctionContextEPNS1_9StringValE",
diff --git a/gensrc/script/doris_builtins_functions.py b/gensrc/script/doris_builtins_functions.py
index 9516371f834988..d9e1f6edb8aa93 100755
--- a/gensrc/script/doris_builtins_functions.py
+++ b/gensrc/script/doris_builtins_functions.py
@@ -630,9 +630,9 @@
     #hll function
     [['hll_cardinality'], 'BIGINT', ['VARCHAR'],
         '_ZN5doris12HllFunctions15hll_cardinalityEPN9doris_udf15FunctionContextERKNS1_9StringValE'],
-    [['hll_hash'], 'VARCHAR', ['VARCHAR'],
+    [['hll_hash'], 'HLL', ['VARCHAR'],
         '_ZN5doris12HllFunctions8hll_hashEPN9doris_udf15FunctionContextERKNS1_9StringValE'],
-    [['hll_empty'], 'VARCHAR', [],
+    [['hll_empty'], 'HLL', [],
         '_ZN5doris12HllFunctions9hll_emptyEPN9doris_udf15FunctionContextE'],
 
     #bitmap function