diff --git a/src/repositories/conversation_repository.py b/src/repositories/conversation_repository.py
index 4b0cd3b76..018fb1806 100644
--- a/src/repositories/conversation_repository.py
+++ b/src/repositories/conversation_repository.py
@@ -12,11 +12,26 @@
 from src.utils import logger
 from src.utils.datetime_utils import utc_now_naive
 
+MAX_CONVERSATION_TITLE_LENGTH = 255
+
 
 class ConversationRepository:
     def __init__(self, db_session: AsyncSession):
         self.db = db_session
 
+    def _normalize_title(self, title: str | None) -> str | None:
+        if title is None:
+            return None
+        normalized = str(title).strip()
+        if not normalized:
+            return ""
+        if len(normalized) > MAX_CONVERSATION_TITLE_LENGTH:
+            logger.warning(
+                f"Conversation title too long ({len(normalized)}), truncate to {MAX_CONVERSATION_TITLE_LENGTH}"
+            )
+            return normalized[:MAX_CONVERSATION_TITLE_LENGTH]
+        return normalized
+
     async def create_conversation(
         self,
         user_id: str,
@@ -31,11 +46,13 @@ async def create_conversation(
         metadata = (metadata or {}).copy()
         metadata.setdefault("attachments", [])
 
+        normalized_title = self._normalize_title(title)
+
         conversation = Conversation(
             thread_id=thread_id,
             user_id=str(user_id),
             agent_id=agent_id,
-            title=title or "New Conversation",
+            title=normalized_title or "New Conversation",
             status="active",
             extra_metadata=metadata,
         )
@@ -203,8 +220,9 @@ async def update_conversation(
         if not conversation:
             return None
 
-        if title is not None:
-            conversation.title = title
+        normalized_title = self._normalize_title(title)
+        if normalized_title is not None:
+            conversation.title = normalized_title
         if status is not None:
             conversation.status = status
 
diff --git a/test/test_conversation_repository.py b/test/test_conversation_repository.py
new file mode 100644
index 000000000..8729223f1
--- /dev/null
+++ b/test/test_conversation_repository.py
@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from src.repositories.conversation_repository import ConversationRepository, MAX_CONVERSATION_TITLE_LENGTH
+
+
+def test_normalize_title_truncates_when_too_long():
+    repo = ConversationRepository(None)  # type: ignore[arg-type]
+    raw = "a" * (MAX_CONVERSATION_TITLE_LENGTH + 50)
+
+    normalized = repo._normalize_title(raw)
+
+    assert normalized is not None
+    assert len(normalized) == MAX_CONVERSATION_TITLE_LENGTH
+    assert normalized == "a" * MAX_CONVERSATION_TITLE_LENGTH
+
+
+def test_normalize_title_trims_spaces():
+    repo = ConversationRepository(None)  # type: ignore[arg-type]
+
+    normalized = repo._normalize_title("   hello world   ")
+
+    assert normalized == "hello world"
diff --git a/web/src/components/AgentChatComponent.vue b/web/src/components/AgentChatComponent.vue
index d777dca22..b2468efaf 100644
--- a/web/src/components/AgentChatComponent.vue
+++ b/web/src/components/AgentChatComponent.vue
@@ -626,12 +626,15 @@ const deleteThread = async (threadId) => {
 const updateThread = async (threadId, title) => {
   if (!threadId || !title) return
 
+  const normalizedTitle = String(title).replace(/\s+/g, ' ').trim().slice(0, 255)
+  if (!normalizedTitle) return
+
   chatState.isRenamingThread = true
   try {
-    await threadApi.updateThread(threadId, title)
+    await threadApi.updateThread(threadId, normalizedTitle)
     const thread = threads.value.find((t) => t.id === threadId)
     if (thread) {
-      thread.title = title
+      thread.title = normalizedTitle
     }
   } catch (error) {
     console.error('Failed to update thread:', error)
@@ -750,7 +753,10 @@ const sendMessage = async ({
 
   // 如果是新对话，用消息内容作为标题
   if ((threadMessages.value[threadId] || []).length === 0) {
-    updateThread(threadId, text)
+    const autoTitle = text.replace(/\s+/g, ' ').trim().slice(0, 255)
+    if (autoTitle) {
+      void updateThread(threadId, autoTitle).catch(() => {})
+    }
   }
 
   const requestData = {