diff --git a/backend/internal/service/channel_monitor_runner.go b/backend/internal/service/channel_monitor_runner.go
index 748ffc3638..dbf03c2395 100644
--- a/backend/internal/service/channel_monitor_runner.go
+++ b/backend/internal/service/channel_monitor_runner.go
@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"errors"
 	"log/slog"
 	"math/rand/v2"
 	"sync"
@@ -139,14 +140,14 @@ func (r *ChannelMonitorRunner) Start() {
 }
 
 // Schedule 为指定监控创建（或重置）独立定时任务。
-//   - m.Enabled=false → 等同于 Unschedule(m.ID)
+//   - m.Enabled=false 或 APIKeyDecryptFailed=true → 等同于 Unschedule(m.ID)
 //   - 已存在的任务会先被取消再重建（适用于 IntervalSeconds 变更场景）
 //   - 新任务立即触发首次检测，之后按 IntervalSeconds 周期触发
 func (r *ChannelMonitorRunner) Schedule(m *ChannelMonitor) {
 	if r == nil || m == nil {
 		return
 	}
-	if !m.Enabled {
+	if !m.Enabled || m.APIKeyDecryptFailed {
 		r.Unschedule(m.ID)
 		return
 	}
@@ -293,7 +294,7 @@ func (r *ChannelMonitorRunner) releaseInFlight(id int64) {
 	r.inFlightMu.Unlock()
 }
 
-// runOne 执行单个监控的检测。所有错误只记日志，不熔断。
+// runOne 执行单个监控的检测。普通错误只记日志；API key 解密失败会撤销任务。
 // 任务结束时（含 panic recover）必须释放 in-flight 槽。
 func (r *ChannelMonitorRunner) runOne(id int64, name string) {
 	ctx, cancel := context.WithTimeout(context.Background(), monitorRequestTimeout+monitorPingTimeout+monitorRunOneBuffer)
@@ -309,6 +310,9 @@ func (r *ChannelMonitorRunner) runOne(id int64, name string) {
 	}()
 
 	if _, err := r.svc.RunCheck(ctx, id); err != nil {
+		if errors.Is(err, ErrChannelMonitorAPIKeyDecryptFailed) {
+			r.Unschedule(id)
+		}
 		slog.Warn("channel_monitor: run check failed",
 			"monitor_id", id, "name", name, "error", err)
 	}
diff --git a/backend/internal/service/channel_monitor_runner_test.go b/backend/internal/service/channel_monitor_runner_test.go
index 5eed3c2092..e1a9b3cccb 100644
--- a/backend/internal/service/channel_monitor_runner_test.go
+++ b/backend/internal/service/channel_monitor_runner_test.go
@@ -159,6 +159,70 @@ func TestSchedule_DisabledRedirectsToUnschedule(t *testing.T) {
 	stoppedWithin(t, r, 3*time.Second)
 }
 
+func TestSchedule_DecryptFailedRedirectsToUnschedule(t *testing.T) {
+	svc := &stubMonitorSvc{runCalled: make(chan int64, 4)}
+	r := newRunnerForTest(svc)
+	r.Start()
+
+	r.Schedule(&ChannelMonitor{ID: 10, Enabled: true, IntervalSeconds: 60})
+	waitFor(t, time.Second, "task registered", func() bool { return runnerTaskCount(r) == 1 })
+
+	r.Schedule(&ChannelMonitor{ID: 10, Enabled: true, IntervalSeconds: 60, APIKeyDecryptFailed: true})
+	if got := runnerTaskCount(r); got != 0 {
+		t.Fatalf("expected tasks empty after decrypt-failed re-Schedule, got %d", got)
+	}
+
+	stoppedWithin(t, r, 3*time.Second)
+}
+
+func TestSchedule_RepairedAPIKeyCanBeScheduled(t *testing.T) {
+	svc := &stubMonitorSvc{runCalled: make(chan int64, 1)}
+	r := newRunnerForTest(svc)
+	r.Start()
+
+	r.Schedule(&ChannelMonitor{ID: 11, Enabled: true, IntervalSeconds: 60, APIKeyDecryptFailed: true})
+	if got := runnerTaskCount(r); got != 0 {
+		t.Fatalf("expected no task for decrypt-failed monitor, got %d", got)
+	}
+
+	r.Schedule(&ChannelMonitor{ID: 11, Enabled: true, IntervalSeconds: 60, APIKey: "replacement-key"})
+	if got := runnerTaskCount(r); got != 1 {
+		t.Fatalf("expected repaired monitor to be scheduled, got %d tasks", got)
+	}
+	select {
+	case id := <-svc.runCalled:
+		if id != 11 {
+			t.Fatalf("expected repaired monitor id=11 to fire, got %d", id)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("expected repaired monitor to fire immediately")
+	}
+
+	stoppedWithin(t, r, 3*time.Second)
+}
+
+func TestRunOne_DecryptFailureUnschedulesTask(t *testing.T) {
+	svc := &stubMonitorSvc{
+		runCalled: make(chan int64, 1),
+		runErr:    ErrChannelMonitorAPIKeyDecryptFailed,
+	}
+	r := newRunnerForTest(svc)
+	r.Start()
+
+	r.Schedule(&ChannelMonitor{ID: 12, Enabled: true, IntervalSeconds: 60})
+	select {
+	case id := <-svc.runCalled:
+		if id != 12 {
+			t.Fatalf("expected failing monitor id=12 to fire, got %d", id)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatal("expected failing monitor to fire immediately")
+	}
+	waitFor(t, time.Second, "decrypt-failed task unscheduled", func() bool { return runnerTaskCount(r) == 0 })
+
+	stoppedWithin(t, r, 3*time.Second)
+}
+
 // TestSchedule_InvalidIntervalSkipped 验证 IntervalSeconds<=0 不会注册任务（防御性检查）。
 func TestSchedule_InvalidIntervalSkipped(t *testing.T) {
 	svc := &stubMonitorSvc{}
@@ -201,6 +265,25 @@ func TestStart_LoadsAllEnabledMonitors(t *testing.T) {
 	stoppedWithin(t, r, 3*time.Second)
 }
 
+func TestStart_SkipsDecryptFailedMonitor(t *testing.T) {
+	svc := &stubMonitorSvc{
+		enabled: []*ChannelMonitor{
+			{ID: 4, Enabled: true, IntervalSeconds: 60, APIKeyDecryptFailed: true},
+		},
+	}
+	r := newRunnerForTest(svc)
+	r.Start()
+
+	if got := runnerTaskCount(r); got != 0 {
+		t.Fatalf("expected no task for decrypt-failed startup monitor, got %d", got)
+	}
+	if got := svc.runCount.Load(); got != 0 {
+		t.Fatalf("expected decrypt-failed startup monitor not to run, got %d calls", got)
+	}
+
+	stoppedWithin(t, r, 3*time.Second)
+}
+
 // TestStop_DrainsAllGoroutines 验证 Stop 会等待所有调度 goroutine 退出（无游离）。
 func TestStop_DrainsAllGoroutines(t *testing.T) {
 	svc := &stubMonitorSvc{}