diff --git a/ets2panda/checker/types/ets/etsUnionType.cpp b/ets2panda/checker/types/ets/etsUnionType.cpp
index 7b94a5311209335cc121aade18da8c1fcaf2d8d4..b3939931c2c52435546bc98997d618cffa4e72b2 100644
--- a/ets2panda/checker/types/ets/etsUnionType.cpp
+++ b/ets2panda/checker/types/ets/etsUnionType.cpp
@@ -194,15 +194,26 @@ void ETSUnionType::CastTarget(TypeRelation *relation, Type *source)
     RelationTarget(relation, source, relFn);
 }
 
+static bool IsStringEnumtypeOf(Type *const super, Type *const sub)
+{
+    if (!super->IsETSStringType() || sub == nullptr) {
+        return false;
+    }
+    if (sub->IsETSStringEnumType()) {
+        return true;
+    }
+    return false;
+}
+
 static std::optional<Type *> TryMergeTypes(TypeRelation *relation, Type *const t1, Type *const t2)
 {
     auto *const checker = relation->GetChecker()->AsETSChecker();
     auto *const never = checker->GetGlobalTypesHolder()->GlobalETSNeverType();
 
-    if (relation->IsSupertypeOf(t1, t2) || t2 == never) {
+    if (relation->IsSupertypeOf(t1, t2) || IsStringEnumtypeOf(t1, t2) || t2 == never) {
         return t1;
     }
-    if (relation->IsSupertypeOf(t2, t1) || t1 == never) {
+    if (relation->IsSupertypeOf(t2, t1) || IsStringEnumtypeOf(t2, t1) || t1 == never) {
         return t2;
     }
     return std::nullopt;
diff --git a/ets2panda/test/ast/compiler/ets/enum_stringEnum_as_string.ets b/ets2panda/test/ast/compiler/ets/enum_stringEnum_as_string.ets
new file mode 100644
index 0000000000000000000000000000000000000000..b2371f411fe754fe8267ed1b8b034f7d4827aa72
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/enum_stringEnum_as_string.ets
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+enum StringEnum {
+    A = "A",
+    B = "B",
+    C = "C"
+}
+
+enum IntEnum {
+    A = 1,
+    B = 2,
+    C = 3
+}
+
+let a: string = StringEnum.A;
+let b: string = /* @@ label */IntEnum.A;
+
+/* @@@ label Error TypeError: Type 'IntEnum' cannot be assigned to type 'String' */
diff --git a/ets2panda/test/ast/compiler/ets/enum_stringEnum_as_union.ets b/ets2panda/test/ast/compiler/ets/enum_stringEnum_as_union.ets
new file mode 100644
index 0000000000000000000000000000000000000000..fa9547e23276e432172dfa92ca7e9f31fcb4b237
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/enum_stringEnum_as_union.ets
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+enum StringEnum {
+    A = "A",
+    B = "B",
+    C = "C"
+}
+
+type UTA = string | StringEnum | number;
+
+let a: UTA = StringEnum.A;
+
+let b: string = /* @@ label */a;
+
+/* @@@ label Error TypeError: Type 'String|Double' cannot be assigned to type 'String' */
diff --git a/ets2panda/test/runtime/ets/enum_stringEnum_as_string.ets b/ets2panda/test/runtime/ets/enum_stringEnum_as_string.ets
new file mode 100644
index 0000000000000000000000000000000000000000..77f73fb89ea2e29570686e2b5d019e28894cfe67
--- /dev/null
+++ b/ets2panda/test/runtime/ets/enum_stringEnum_as_string.ets
@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+enum StringEnum {
+    A = "A",
+    B = "B",
+    C = "C"
+}
+
+interface I {
+    a: string;
+}
+
+function foo(a: string): string {
+    return a;
+}
+
+let a: string = StringEnum.A;
+assertEQ(a, "A");
+let i: I = { a: StringEnum.B };
+assertEQ(i.a, "B");
+assertEQ(foo(StringEnum.C), "C");
diff --git a/ets2panda/test/runtime/ets/enum_stringEnum_as_union.ets b/ets2panda/test/runtime/ets/enum_stringEnum_as_union.ets
new file mode 100644
index 0000000000000000000000000000000000000000..b9a975796d1735c7cde2dff05285f2cdcb61bd41
--- /dev/null
+++ b/ets2panda/test/runtime/ets/enum_stringEnum_as_union.ets
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+enum StringEnum {
+    A = "A",
+    B = "B",
+    C = "C"
+}
+
+class C {
+    public a: string | StringEnum = StringEnum.A;
+}
+
+interface I {
+    a: string | StringEnum;
+}
+
+type UTA = string | StringEnum | number;
+
+function foo(a: string | StringEnum): string {
+    return a;
+}
+
+function main() {
+    let a: UTA = StringEnum.A;
+    let b: string | number = a;
+    assertEQ(a, b);
+    assertEQ(b, "A");
+    assertEQ(foo(StringEnum.B), "B");
+    // class
+    let c: C = new C();
+    assertEQ(c.a, "A");
+    // interface
+    let i: I = { a: StringEnum.C };
+    assertEQ(i.a, "C");
+}