diff --git a/pkg/ttl/ttlworker/BUILD.bazel b/pkg/ttl/ttlworker/BUILD.bazel
index df18effc77bec..59aa1033e5e5c 100644
--- a/pkg/ttl/ttlworker/BUILD.bazel
+++ b/pkg/ttl/ttlworker/BUILD.bazel
@@ -67,6 +67,7 @@ go_test(
         "task_manager_test.go",
         "timer_sync_test.go",
         "timer_test.go",
+        "worker_test.go",
     ],
     embed = [":ttlworker"],
     flaky = True,
@@ -100,6 +101,7 @@ go_test(
         "//pkg/util/chunk",
         "//pkg/util/logutil",
         "//pkg/util/mock",
+        "//pkg/util/timeutil",
         "@com_github_google_uuid//:uuid",
         "@com_github_ngaut_pools//:pools",
         "@com_github_pingcap_errors//:errors",
diff --git a/pkg/ttl/ttlworker/scan.go b/pkg/ttl/ttlworker/scan.go
index 9a01009e2f15b..d28f62b8734a3 100644
--- a/pkg/ttl/ttlworker/scan.go
+++ b/pkg/ttl/ttlworker/scan.go
@@ -30,6 +30,7 @@ import (
 	"github.com/pingcap/tidb/pkg/types"
 	"github.com/pingcap/tidb/pkg/util"
 	"github.com/pingcap/tidb/pkg/util/chunk"
+	"github.com/pingcap/tidb/pkg/util/intest"
 	"github.com/pingcap/tidb/pkg/util/logutil"
 	"go.uber.org/zap"
 )
@@ -41,6 +42,9 @@ var (
 	taskMaxErrorRate                = 0.4
 )
 
+// TTLScanPostScanHookForTest is used to hook the cancel of the TTL scan task. It's only used in tests.
+type TTLScanPostScanHookForTest struct{}
+
 type ttlStatistics struct {
 	TotalRows   atomic.Uint64
 	SuccessRows atomic.Uint64
@@ -380,6 +384,10 @@ func (w *ttlScanWorker) handleScanTask(tracer *metrics.PhaseTracer, task *ttlSca
 		result = task.result(nil)
 	}
 
+	if intest.InTest && ctx.Value(TTLScanPostScanHookForTest{}) != nil {
+		ctx.Value(TTLScanPostScanHookForTest{}).(func())()
+	}
+
 	w.baseWorker.Lock()
 	w.curTaskResult = result
 	w.baseWorker.Unlock()
diff --git a/pkg/ttl/ttlworker/task_manager.go b/pkg/ttl/ttlworker/task_manager.go
index fafd97247f608..cf4e531008eed 100644
--- a/pkg/ttl/ttlworker/task_manager.go
+++ b/pkg/ttl/ttlworker/task_manager.go
@@ -160,6 +160,8 @@ func (m *taskManager) resizeScanWorkers(count int) error {
 			jobID = curTask.JobID
 			scanID = curTask.ScanID
 			scanErr = errors.New("timeout to cancel scan task")
+
+			result = curTask.result(scanErr)
 		}
 
 		task := findTaskWithID(m.runningTasks, jobID, scanID)
diff --git a/pkg/ttl/ttlworker/task_manager_integration_test.go b/pkg/ttl/ttlworker/task_manager_integration_test.go
index 93ab32d1d3875..e88332198187e 100644
--- a/pkg/ttl/ttlworker/task_manager_integration_test.go
+++ b/pkg/ttl/ttlworker/task_manager_integration_test.go
@@ -356,3 +356,72 @@ func TestMeetTTLRunningTasks(t *testing.T) {
 	require.False(t, dom.TTLJobManager().TaskManager().MeetTTLRunningTasks(3, cache.TaskStatusWaiting))
 	require.True(t, dom.TTLJobManager().TaskManager().MeetTTLRunningTasks(3, cache.TaskStatusRunning))
 }
+
+func TestShrinkScanWorkerTimeout(t *testing.T) {
+	store, dom := testkit.CreateMockStoreAndDomain(t)
+	pool := wrapPoolForTest(dom.SysSessionPool())
+	defer pool.AssertNoSessionInUse(t)
+	waitAndStopTTLManager(t, dom)
+	tk := testkit.NewTestKit(t, store)
+	sessionFactory := sessionFactory(t, store)
+
+	tk.MustExec("set global tidb_ttl_running_tasks = 32")
+
+	tk.MustExec("create table test.t(id int, created_at datetime) ttl=created_at + interval 1 day")
+	testTable, err := dom.InfoSchema().TableByName(context.Background(), model.NewCIStr("test"), model.NewCIStr("t"))
+	require.NoError(t, err)
+	for id := 0; id < 4; id++ {
+		sql := fmt.Sprintf("insert into mysql.tidb_ttl_task(job_id,table_id,scan_id,expire_time,created_time) values ('test-job', %d, %d, NOW() - INTERVAL 1 DAY, NOW())", testTable.Meta().ID, id)
+		tk.MustExec(sql)
+	}
+
+	se := sessionFactory()
+	now := se.Now()
+
+	isc := cache.NewInfoSchemaCache(time.Minute)
+	require.NoError(t, isc.Update(se))
+	m := ttlworker.NewTaskManager(context.Background(), pool, isc, "scan-manager-1", store)
+	workers := []ttlworker.Worker{}
+	for j := 0; j < 4; j++ {
+		scanWorker := ttlworker.NewMockScanWorker(t)
+		scanWorker.Start()
+		workers = append(workers, scanWorker)
+	}
+
+	startBlockNotifyCh := make(chan struct{})
+	blockCancelCh := make(chan struct{})
+	workers[0].(ttlworker.WorkerTestExt).SetCtx(func(ctx context.Context) context.Context {
+		return context.WithValue(ctx, ttlworker.TTLScanPostScanHookForTest{}, func() {
+			startBlockNotifyCh <- struct{}{}
+			<-blockCancelCh
+		})
+	})
+	m.SetScanWorkers4Test(workers)
+
+	m.RescheduleTasks(se, now)
+	require.Len(t, m.GetRunningTasks(), 4)
+	tk.MustQuery("SELECT count(1) from mysql.tidb_ttl_task where status = 'running'").Check(testkit.Rows("4"))
+	<-startBlockNotifyCh
+
+	// shrink scan workers, one of them will timeout
+	require.Error(t, m.ResizeScanWorkers(0))
+	require.Len(t, m.GetScanWorkers(), 0)
+
+	// the canceled 3 tasks are still running, but they have results, so after `CheckFinishedTask`, it should be finished
+	tk.MustQuery("SELECT count(1) from mysql.tidb_ttl_task where status = 'running'").Check(testkit.Rows("4"))
+	m.CheckFinishedTask(se, now)
+	require.Len(t, m.GetRunningTasks(), 0)
+	// now, the task should be finished
+	tk.MustQuery("SELECT count(1) from mysql.tidb_ttl_task where status = 'running'").Check(testkit.Rows("0"))
+	// the first task will be finished with "timeout to cancel scan task"
+	// other tasks will finish with table not found because we didn't mock the table in this test.
+	tk.MustQuery("SELECT scan_id, json_extract(state, '$.scan_task_err') from mysql.tidb_ttl_task").Sort().Check(testkit.Rows(
+		"0 \"timeout to cancel scan task\"",
+		"1 \"table 'test.t' meta changed, should abort current job: [schema:1146]Table 'test.t' doesn't exist\"",
+		"2 \"table 'test.t' meta changed, should abort current job: [schema:1146]Table 'test.t' doesn't exist\"",
+		"3 \"table 'test.t' meta changed, should abort current job: [schema:1146]Table 'test.t' doesn't exist\"",
+	))
+
+	require.NoError(t, m.ResizeDelWorkers(0))
+	close(blockCancelCh)
+}
diff --git a/pkg/ttl/ttlworker/task_manager_test.go b/pkg/ttl/ttlworker/task_manager_test.go
index 064c68f86ed40..2ff3bb212a043 100644
--- a/pkg/ttl/ttlworker/task_manager_test.go
+++ b/pkg/ttl/ttlworker/task_manager_test.go
@@ -56,6 +56,16 @@ func (m *taskManager) RescheduleTasks(se session.Session, now time.Time) {
 	m.rescheduleTasks(se, now)
 }
 
+// ResizeScanWorkers is an exported version of resizeScanWorkers
+func (m *taskManager) ResizeScanWorkers(count int) error {
+	return m.resizeScanWorkers(count)
+}
+
+// ResizeDelWorkers is an exported version of resizeDeleteWorkers
+func (m *taskManager) ResizeDelWorkers(count int) error {
+	return m.resizeDelWorkers(count)
+}
+
 // ReportMetrics is an exported version of reportMetrics
 func (m *taskManager) ReportMetrics() {
 	m.reportMetrics()
@@ -81,6 +91,11 @@ func (m *taskManager) ReportTaskFinished(se session.Session, now time.Time, task
 	return m.reportTaskFinished(se, now, task)
 }
 
+// GetScanWorkers returns the scan workers of the task manager.
+func (m *taskManager) GetScanWorkers() []worker {
+	return m.scanWorkers
+}
+
 // SetResult sets the result of the task
 func (t *runningScanTask) SetResult(err error) {
 	t.result = t.ttlScanTask.result(err)
diff --git a/pkg/ttl/ttlworker/timer_test.go b/pkg/ttl/ttlworker/timer_test.go
index 12bedc8e0cf41..b0400bc53f7a7 100644
--- a/pkg/ttl/ttlworker/timer_test.go
+++ b/pkg/ttl/ttlworker/timer_test.go
@@ -27,6 +27,7 @@ import (
 	"github.com/pingcap/tidb/pkg/sessionctx/variable"
 	timerapi "github.com/pingcap/tidb/pkg/timer/api"
 	"github.com/pingcap/tidb/pkg/util/logutil"
+	"github.com/pingcap/tidb/pkg/util/timeutil"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
 )
@@ -350,8 +351,9 @@ func TestTTLTimerHookOnEvent(t *testing.T) {
 	require.Equal(t, summaryData, timer.SummaryData)
 	adapter.AssertExpectations(t)
 
+	tz := timeutil.SystemLocation()
 	// job not exists but table ttl not enabled
-	watermark := time.Unix(3600*123, 0)
+	watermark := time.Unix(3600*123, 0).In(tz)
 	require.NoError(t, cli.UpdateTimer(ctx, timer.ID, timerapi.WithSetWatermark(watermark)))
 	timer = triggerTestTimer(t, store, timer.ID)
 	adapter.On("GetJob", ctx, data.TableID, data.PhysicalID, timer.EventID).
@@ -373,7 +375,7 @@ func TestTTLTimerHookOnEvent(t *testing.T) {
 	require.Equal(t, oldSummary, timer.SummaryData)
 
 	// job not exists but timer disabled
-	watermark = time.Unix(3600*456, 0)
+	watermark = time.Unix(3600*456, 0).In(tz)
 	require.NoError(t, cli.UpdateTimer(ctx, timer.ID, timerapi.WithSetWatermark(watermark), timerapi.WithSetEnable(false)))
 	timer = triggerTestTimer(t, store, timer.ID)
 	adapter.On("GetJob", ctx, data.TableID, data.PhysicalID, timer.EventID).
@@ -394,7 +396,7 @@ func TestTTLTimerHookOnEvent(t *testing.T) {
 	require.NoError(t, cli.UpdateTimer(ctx, timer.ID, timerapi.WithSetEnable(true)))
 
 	// job not exists but event start too early
-	watermark = time.Unix(3600*789, 0)
+	watermark = time.Unix(3600*789, 0).In(tz)
 	require.NoError(t, cli.UpdateTimer(ctx, timer.ID, timerapi.WithSetWatermark(watermark)))
 	timer = triggerTestTimer(t, store, timer.ID)
 	adapter.On("Now").Return(timer.EventStart.Add(11*time.Minute), nil).Once()
diff --git a/pkg/ttl/ttlworker/worker_test.go b/pkg/ttl/ttlworker/worker_test.go
new file mode 100644
index 0000000000000..0291cd538c24c
--- /dev/null
+++ b/pkg/ttl/ttlworker/worker_test.go
@@ -0,0 +1,29 @@
+// Copyright 2024 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ttlworker
+
+import "context"
+
+// WorkerTestExt is the extension interface for worker in test.
+type WorkerTestExt interface {
+	SetCtx(f func(ctx context.Context) context.Context)
+}
+
+var _ WorkerTestExt = &baseWorker{}
+
+// SetCtx modifies the context of the worker.
+func (w *baseWorker) SetCtx(f func(ctx context.Context) context.Context) {
+	w.ctx = f(w.ctx)
+}