diff --git a/packages/services/agent-service/src/infrastructure/wecom/wecom-router.service.ts b/packages/services/agent-service/src/infrastructure/wecom/wecom-router.service.ts
index cdb438e..16cdebd 100644
--- a/packages/services/agent-service/src/infrastructure/wecom/wecom-router.service.ts
+++ b/packages/services/agent-service/src/infrastructure/wecom/wecom-router.service.ts
@@ -56,7 +56,7 @@ const CODE_TTL_MS              = 15 * 60 * 1000;
 const TASK_TIMEOUT_S           = 120;
 const CALLBACK_TIMEOUT_MS      = 180_000;
 const THINKING_REMINDER_MS     = 25_000;
-const DEDUP_TTL_MS             = 10 * 60 * 1000;
+const DEDUP_TTL_S              = 10 * 60;   // Redis key TTL for dedup
 const RATE_LIMIT_PER_MIN       = 10;
 const QUEUE_MAX_DEPTH          = 5;
 const CLEANUP_INTERVAL_MS      = 5 * 60 * 1000;
@@ -119,9 +119,8 @@ export class WecomRouterService implements OnModuleInit, OnModuleDestroy {
   private redis?: Redis;
 
   // State maps
-  private readonly bindingCodes     = new Map<string, BindingEntry>();
-  private readonly dedup            = new Map<string, number>();
-  private readonly rateWindows      = new Map<string, number[]>();
+  private readonly bindingCodes = new Map<string, BindingEntry>();
+  private readonly rateWindows  = new Map<string, number[]>();
   private readonly queueTails       = new Map<string, Promise<void>>();
   private readonly queueDepths      = new Map<string, number>();
   private readonly pendingCallbacks = new Map<string, {
@@ -219,6 +218,23 @@ export class WecomRouterService implements OnModuleInit, OnModuleDestroy {
     } catch { /* non-fatal */ }
   }
 
+  /**
+   * Dedup check using Redis SET NX EX.
+   * Returns true if this is the FIRST time we've seen this msgId (should process).
+   * Returns false if already seen (duplicate — skip).
+   * Falls back to true (process) if Redis is unavailable, to avoid silent drops.
+   */
+  private async redisDedup(msgId: string): Promise<boolean> {
+    if (!this.redis) return true; // no Redis → process (fail open for dedup only)
+    try {
+      const key    = `wecom:dedup:${msgId}`;
+      const result = await this.redis.set(key, '1', 'EX', DEDUP_TTL_S, 'NX');
+      return result === 'OK'; // 'OK' = first time; null = already exists
+    } catch {
+      return true; // Redis error → process rather than drop
+    }
+  }
+
   private async redisGetAndDelPending(msgId: string): Promise<string | null> {
     if (!this.redis) return null;
     try {
@@ -509,8 +525,8 @@ export class WecomRouterService implements OnModuleInit, OnModuleDestroy {
 
   private async handleMessage(msg: WecomMsg, msgType: string): Promise<void> {
     if (!msg.externalUserId || !msg.msgId) return;
-    if (this.dedup.has(msg.msgId)) return;
-    this.dedup.set(msg.msgId, Date.now());
+    const isNew = await this.redisDedup(msg.msgId);
+    if (!isNew) return;
 
     this.logger.log(`WeCom message: externalUserId=${msg.externalUserId} type=${msgType} msgId=${msg.msgId}`);
 
@@ -779,8 +795,6 @@ export class WecomRouterService implements OnModuleInit, OnModuleDestroy {
 
   private periodicCleanup(): void {
     const now = Date.now();
-    for (const [id, ts] of this.dedup)
-      if (now - ts > DEDUP_TTL_MS) this.dedup.delete(id);
     for (const [userId, timestamps] of this.rateWindows) {
       const fresh = timestamps.filter(t => now - t < 60_000);
       if (fresh.length === 0) this.rateWindows.delete(userId);