diff --git a/src/app/api/auth/register/route.ts b/src/app/api/auth/register/route.ts
index 9ac66fe..8eef105 100644
--- a/src/app/api/auth/register/route.ts
+++ b/src/app/api/auth/register/route.ts
@@ -128,7 +128,7 @@ export async function POST(request: NextRequest) {
       cchUrl: process.env.CCH_DEFAULT_URL || 'https://claude.leocoder.cn/',
       cchApiKey: null,
       cchApiKeyConfigured: false,
-      defaultModel: 'claude-sonnet-4-20250514',
+      defaultModel: 'claude-sonnet-4-5-20250929',
       defaultTools: ['web_search', 'code_execution', 'web_fetch'],
       theme: 'light',
       language: 'zh-CN',
diff --git a/src/app/api/conversations/route.ts b/src/app/api/conversations/route.ts
index 2a6a84a..a1c9013 100644
--- a/src/app/api/conversations/route.ts
+++ b/src/app/api/conversations/route.ts
@@ -57,7 +57,7 @@ export async function POST(request: Request) {
       .values({
         conversationId,
         title: title || '新对话',
-        model: model || 'claude-sonnet-4-20250514',
+        model: model || 'claude-sonnet-4-5-20250929',
         tools: tools || [],
         enableThinking: enableThinking || false,
         userId: user.userId, // 关联当前用户
diff --git a/src/app/assistants/page.tsx b/src/app/assistants/page.tsx
index 31f1e08..080914c 100644
--- a/src/app/assistants/page.tsx
+++ b/src/app/assistants/page.tsx
@@ -152,7 +152,7 @@ export default function AssistantsPage() {
 
       // 创建新对话
       const newConversation = await createConversation({
-        model: settings?.defaultModel || 'claude-sonnet-4-20250514',
+        model: settings?.defaultModel || 'claude-sonnet-4-5-20250929',
         tools: settings?.defaultTools || [],
         enableThinking: settings?.enableThinking || false,
         assistantId: assistant.id,
diff --git a/src/components/features/NewChatModal.tsx b/src/components/features/NewChatModal.tsx
index d10ff03..71fb121 100644
--- a/src/components/features/NewChatModal.tsx
+++ b/src/components/features/NewChatModal.tsx
@@ -111,7 +111,7 @@ export function NewChatModal({ isOpen, onClose }: NewChatModalProps) {
     setIsCreating(true);
     try {
       const newConversation = await createConversation({
-        model: settings?.defaultModel || 'claude-sonnet-4-20250514',
+        model: settings?.defaultModel || 'claude-sonnet-4-5-20250929',
         tools: settings?.defaultTools || [],
         enableThinking: settings?.enableThinking || false,
         assistantId: assistant?.id,