diff --git a/ets2panda/compiler/lowering/ets/defaultParametersLowering.cpp b/ets2panda/compiler/lowering/ets/defaultParametersLowering.cpp
index d87fc777fd5283328aa9c22b3f21b944ac3cc7c2..b525f3c4f84375b4ab1a608f7b6265805aa8961b 100644
--- a/ets2panda/compiler/lowering/ets/defaultParametersLowering.cpp
+++ b/ets2panda/compiler/lowering/ets/defaultParametersLowering.cpp
@@ -16,6 +16,8 @@
 #include "defaultParametersLowering.h"
 #include "compiler/lowering/util.h"
 
+#include <checker/ETSchecker.h>
+
 namespace ark::es2panda::compiler {
 
 static ir::Statement *TransformInitializer(ArenaAllocator *allocator, parser::ETSParser *parser,
@@ -38,6 +40,20 @@ static ir::Statement *TransformInitializer(ArenaAllocator *allocator, parser::ET
                                             param->Ident()->Name(), init, typeAnnotation->Clone(allocator, nullptr));
 }
 
+static void ValidateDefaultParamInDeclare(public_lib::Context *ctx, ir::ScriptFunction *function,
+                                          std::vector<ir::ETSParameterExpression *> &params)
+{
+    for (auto param : params) {
+        if (param->Initializer() == nullptr) {
+            continue;
+        }
+        param->SetInitializer(nullptr);
+        if ((function->Flags() & ir::ScriptFunctionFlags::EXTERNAL) != 0U) {
+            ctx->checker->AsETSChecker()->LogError(diagnostic::DEFAULT_PARAM_IN_DECLARE, param->Start());
+        }
+    }
+}
+
 static void TransformFunction(public_lib::Context *ctx, ir::ScriptFunction *function)
 {
     auto const &params = function->Params();
@@ -62,7 +78,7 @@ static void TransformFunction(public_lib::Context *ctx, ir::ScriptFunction *func
         return;
     }
     if (!function->HasBody()) {  // #23134
-        ES2PANDA_ASSERT(ctx->diagnosticEngine->IsAnyError());
+        ValidateDefaultParamInDeclare(ctx, function, defaultParams);
         return;
     }
     auto const body = function->Body()->AsBlockStatement();
diff --git a/ets2panda/test/ast/compiler/ets/default_param_declare.ets b/ets2panda/test/ast/compiler/ets/default_param_declare.ets
new file mode 100644
index 0000000000000000000000000000000000000000..491faa15e8776f434ca3093296d3895001dfa6aa
--- /dev/null
+++ b/ets2panda/test/ast/compiler/ets/default_param_declare.ets
@@ -0,0 +1,21 @@
+/*
+ * 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.
+ */
+
+declare class A{
+    foo(/* @@ label1 */a:number = 1, /* @@ label2 */b:int = 2):void
+}
+
+/* @@@ label1 Error SyntaxError: A parameter initializer is only allowed in a function or constructor implementation. */
+/* @@@ label2 Error SyntaxError: A parameter initializer is only allowed in a function or constructor implementation. */
diff --git a/ets2panda/util/diagnostic/syntax.yaml b/ets2panda/util/diagnostic/syntax.yaml
index 465347e084fe629eda60dd36511d7b93fbb3b906..2dd18d400b7f2574ed0cf18f6d6cdd353e9bc545 100644
--- a/ets2panda/util/diagnostic/syntax.yaml
+++ b/ets2panda/util/diagnostic/syntax.yaml
@@ -1195,3 +1195,7 @@ syntax:
 - name: DEEP_NESTING
   id: 306
   message: "Maximum allowed nesting level exceeded."
+
+- name: DEFAULT_PARAM_IN_DECLARE
+  id: 382
+  message: "A parameter initializer is only allowed in a function or constructor implementation."
\ No newline at end of file