diff --git a/mq-starter-core/src/main/java/com/njcn/mq/container/MqConsumeDispatcher.java b/mq-starter-core/src/main/java/com/njcn/mq/container/MqConsumeDispatcher.java
index cd6dcf3..877c63d 100644
--- a/mq-starter-core/src/main/java/com/njcn/mq/container/MqConsumeDispatcher.java
+++ b/mq-starter-core/src/main/java/com/njcn/mq/container/MqConsumeDispatcher.java
@@ -187,7 +187,9 @@ public class MqConsumeDispatcher {
     public static class Builder {
         private int batchSize = 1;
         private int batchTimeoutMs;                              // 缺省 0 = 关闭（注解缺省 60s 由 registry 传入）
-        private LongSupplier clock = System::currentTimeMillis;
+        // 单调时钟:只做相对差值(now - batchStartAtMs),用 nanoTime 免受 NTP 回拨影响
+        // (墙钟回拨会让差值变负,批多躺回拨量,突破"延迟上界一个超时窗口"承诺)。
+        private LongSupplier clock = () -> System.nanoTime() / 1_000_000;
         private boolean idempotent = false;
         private MqIdempotentStore store;
         private MqConsumeErrorHandler errorHandler;
diff --git a/mq-starter-core/src/test/java/com/njcn/mq/container/MqConsumeDispatcherTest.java b/mq-starter-core/src/test/java/com/njcn/mq/container/MqConsumeDispatcherTest.java
index a5ab0ea..09305c6 100644
--- a/mq-starter-core/src/test/java/com/njcn/mq/container/MqConsumeDispatcherTest.java
+++ b/mq-starter-core/src/test/java/com/njcn/mq/container/MqConsumeDispatcherTest.java
@@ -334,6 +334,22 @@ class MqConsumeDispatcherTest {
         assertFalse(d.needsTimeoutFlush(), "关闭超时的批量监听器不应纳入定时扫描");
     }
 
+    @Test
+    void defaultClock_freshBatchNotDue() throws Exception {
+        // 不注入 clock,守护缺省单调时钟的纳秒→毫秒换算:错用裸 nanoTime 会让差值以纳秒计,
+        // 刚入缓冲的批立即被判超时刷出。
+        List<List<MqMessage>> consumed = new ArrayList<>();
+        MqConsumeDispatcher d = MqConsumeDispatcher.builder()
+                .batchSize(3).batchTimeoutMs(60_000)
+                .consumer(consumed::add)
+                .build();
+
+        d.dispatch(MqMessage.of("k1", "", "a"));
+        d.flushIfTimeout();
+
+        assertEquals(0, consumed.size(), "刚入缓冲远未到 60s,缺省时钟不应判超时");
+    }
+
     @Test
     void forceFlush_flushesLeftovers() throws Exception {
         List<List<MqMessage>> consumed = new ArrayList<>();