diff --git a/backend/app/services/scheduler.py b/backend/app/services/scheduler.py
index 10b2ec8..ab6d4b8 100755
--- a/backend/app/services/scheduler.py
+++ b/backend/app/services/scheduler.py
@@ -130,14 +130,13 @@ class SchedulerService:
             # 获取最大并发
             max_concurrent = int(await self._get_config(db, "max_concurrent_users", "5"))
 
-            # 获取已登录、启用的用户
-            query = select(VirtualUser).where(
-                VirtualUser.status == 2,
-                VirtualUser.is_enabled == 1,
+            # 获取所有已登录、启用的用户（不加 LIMIT，确保所有用户公平参与）
+            result = await db.execute(
+                select(VirtualUser).where(
+                    VirtualUser.status == 2,
+                    VirtualUser.is_enabled == 1,
+                )
             )
-            if max_concurrent > 0:
-                query = query.limit(max_concurrent)
-            result = await db.execute(query)
             all_users = result.scalars().all()
 
             # 没有已登录用户时，尝试登录未登录用户
@@ -146,26 +145,39 @@ class SchedulerService:
                 return
 
             # 检查互动间隔：过滤掉最近 min_interval 秒内已互动的用户
-            now_utc = datetime.now()
+            now_dt = datetime.now()
             eligible = []
             for u in all_users:
                 if u.last_interact_at is None:
                     eligible.append(u)
                 else:
-                    elapsed = (now_utc - u.last_interact_at).total_seconds()
+                    elapsed = (now_dt - u.last_interact_at).total_seconds()
                     if elapsed >= min_interval:
                         eligible.append(u)
 
             if not eligible:
-                logger.debug(f"[调度] 所有用户在 {min_interval}s 内已互动，跳过本次")
+                logger.debug(f"[调度] 所有 {len(all_users)} 个用户在 {min_interval}s 内已互动，跳过本次")
                 return
 
-            logger.info(f"[调度] {len(eligible)}/{len(all_users)} 个用户满足间隔要求，开始互动")
+            # 按最后互动时间升序排序：最久没互动的用户优先
+            eligible.sort(key=lambda u: u.last_interact_at or datetime.min)
 
-            # 随机选取用户执行互动
-            for user in eligible:
-                if random.random() < 0.6:
-                    asyncio.create_task(self._execute_user_interaction(user.id))
+            # 从符合条件的用户中随机选取 max_concurrent 个执行（保证公平轮转）
+            batch_size = max_concurrent if max_concurrent > 0 else len(eligible)
+            # 优先选最久未互动的用户（前1/3），其余随机补充
+            priority_size = max(1, batch_size // 3)
+            priority_users = eligible[:priority_size]
+            rest_users = eligible[priority_size:]
+            random.shuffle(rest_users)
+            selected = priority_users + rest_users[:max(0, batch_size - priority_size)]
+
+            logger.info(
+                f"[调度] 共 {len(all_users)} 个用户，{len(eligible)} 个满足间隔，"
+                f"本轮选取 {len(selected)} 个执行互动"
+            )
+
+            for user in selected:
+                asyncio.create_task(self._execute_user_interaction(user.id))
 
     async def _try_login_users(self, db):
         """尝试登录未登录的用户"""