diff --git a/server/schedule/operator/operator.go b/server/schedule/operator/operator.go
index 792778a201a..62638a2271a 100644
--- a/server/schedule/operator/operator.go
+++ b/server/schedule/operator/operator.go
@@ -225,16 +225,12 @@ func (o *Operator) CheckExpired() bool {
 
 // CheckTimeout checks if the operator is timeout, and update the status.
 func (o *Operator) CheckTimeout() bool {
-	if o.CheckSuccess() || len(o.steps) == 0 {
+	if o.CheckSuccess() {
 		return false
 	}
-	currentStep := int(atomic.LoadInt32(&o.currentStep))
-	startTime := o.GetStartTime()
-	if 0 < currentStep && currentStep-1 < len(o.steps) {
-		startTime = time.Unix(0, atomic.LoadInt64(&(o.stepsTime[currentStep-1])))
-	}
-	step := o.steps[currentStep]
-	return o.status.CheckStepTimeout(startTime, step, o.ApproximateSize)
+	currentStep := atomic.LoadInt32(&o.currentStep)
+	startTime := o.getStepStartTime(currentStep)
+	return o.status.CheckStepTimeout(startTime, o.steps[currentStep], o.ApproximateSize)
 }
 
 // Len returns the operator's steps count.
@@ -250,6 +246,15 @@ func (o *Operator) Step(i int) OpStep {
 	return nil
 }
 
+// getStepStartTime returns the start time of the i-th step.
+func (o *Operator) getStepStartTime(step int32) time.Time {
+	startTime := o.GetStartTime()
+	if 0 < step && int(step-1) < len(o.steps) {
+		startTime = time.Unix(0, atomic.LoadInt64(&(o.stepsTime[step-1])))
+	}
+	return startTime
+}
+
 // Check checks if current step is finished, returns next step to take action.
 // If operator is at an end status, check returns nil.
 // It's safe to be called by multiple goroutine concurrently.
@@ -262,14 +267,8 @@ func (o *Operator) Check(region *core.RegionInfo) OpStep {
 	for step := atomic.LoadInt32(&o.currentStep); int(step) < len(o.steps); step++ {
 		if o.steps[int(step)].IsFinish(region) {
 			if atomic.CompareAndSwapInt64(&(o.stepsTime[step]), 0, time.Now().UnixNano()) {
-				var startTime time.Time
-				if step == 0 {
-					startTime = o.GetStartTime()
-				} else {
-					startTime = time.Unix(0, atomic.LoadInt64(&(o.stepsTime[step-1])))
-				}
 				operatorStepDuration.WithLabelValues(reflect.TypeOf(o.steps[int(step)]).Name()).
-					Observe(time.Unix(0, o.stepsTime[step]).Sub(startTime).Seconds())
+					Observe(time.Unix(0, o.stepsTime[step]).Sub(o.getStepStartTime(step)).Seconds())
 			}
 			atomic.StoreInt32(&o.currentStep, step+1)
 		} else {
@@ -405,12 +404,16 @@ func (o *Operator) GetAdditionalInfo() string {
 // these values are used for unit test.
 const (
 	// mock region default region size is 96MB.
-	mockRegionSize = 96 * (1 << 20)
+	mockRegionSize = 96
 	mockDesc       = "test"
 	mockBrief      = "test"
 )
 
 // NewTestOperator creates a test operator, only used for unit test.
 func NewTestOperator(regionID uint64, regionEpoch *metapb.RegionEpoch, kind OpKind, steps ...OpStep) *Operator {
+	// OpSteps can not be empty for test.
+	if len(steps) == 0 {
+		steps = []OpStep{ChangePeerV2Leave{}}
+	}
 	return NewOperator(mockDesc, mockBrief, regionID, regionEpoch, kind, mockRegionSize, steps...)
 }
diff --git a/server/schedule/operator/status_tracker_test.go b/server/schedule/operator/status_tracker_test.go
index aed287d833d..8ada8b386f2 100644
--- a/server/schedule/operator/status_tracker_test.go
+++ b/server/schedule/operator/status_tracker_test.go
@@ -130,6 +130,7 @@ func (s *testOpStatusTrackerSuite) TestCheckStepTimeout(c *C) {
 	}}
 
 	for _, v := range testdata {
+		// Timeout and status changed
 		trk := NewOpStatusTracker()
 		trk.To(STARTED)
 		c.Assert(trk.CheckStepTimeout(v.start, v.step, 0), Equals, v.status == TIMEOUT)
diff --git a/server/schedule/operator/step.go b/server/schedule/operator/step.go
index 3b9e194e172..f8d075577f5 100644
--- a/server/schedule/operator/step.go
+++ b/server/schedule/operator/step.go
@@ -36,7 +36,7 @@ const (
 	// default: 6 s/Mb
 	DefaultSlowExecutorRate = 6
 	// DefaultFastExecutorRate is the slow rate of the operator executor.
-	// default:  0.01 s/Mb
+	// default:  0.1 s/Mb
 	DefaultFastExecutorRate = 0.1
 )
 
@@ -112,7 +112,7 @@ func (tl TransferLeader) Influence(opInfluence OpInfluence, region *core.RegionI
 
 // Timeout returns true if the step is timeout.
 func (tl TransferLeader) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxFastWaitTime(regionSize)
+	return time.Since(start) > fastStepWaitDuration(regionSize)
 }
 
 // AddPeer is an OpStep that adds a region peer.
@@ -170,7 +170,7 @@ func (ap AddPeer) CheckInProgress(ci ClusterInformer, region *core.RegionInfo) e
 
 // Timeout returns true if the step is timeout.
 func (ap AddPeer) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxSlowWaitTime(regionSize)
+	return time.Since(start) > slowStepWaitDuration(regionSize)
 }
 
 // AddLearner is an OpStep that adds a region learner peer.
@@ -234,7 +234,7 @@ func (al AddLearner) Influence(opInfluence OpInfluence, region *core.RegionInfo)
 
 // Timeout returns true if the step is timeout.
 func (al AddLearner) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxSlowWaitTime(regionSize)
+	return time.Since(start) > slowStepWaitDuration(regionSize)
 }
 
 // PromoteLearner is an OpStep that promotes a region learner peer to normal voter.
@@ -277,7 +277,7 @@ func (pl PromoteLearner) Influence(_ OpInfluence, _ *core.RegionInfo) {}
 
 // Timeout returns true if the step is timeout.
 func (pl PromoteLearner) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxFastWaitTime(regionSize)
+	return time.Since(start) > fastStepWaitDuration(regionSize)
 }
 
 // RemovePeer is an OpStep that removes a region peer.
@@ -333,7 +333,7 @@ func (rp RemovePeer) Influence(opInfluence OpInfluence, region *core.RegionInfo)
 
 // Timeout returns true if the step is timeout.
 func (rp RemovePeer) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxFastWaitTime(regionSize)
+	return time.Since(start) > fastStepWaitDuration(regionSize)
 }
 
 // MergeRegion is an OpStep that merge two regions.
@@ -386,7 +386,7 @@ func (mr MergeRegion) Influence(opInfluence OpInfluence, region *core.RegionInfo
 
 // Timeout returns true if the step is timeout.
 func (mr MergeRegion) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxFastWaitTime(regionSize)*10
+	return time.Since(start) > fastStepWaitDuration(regionSize)*10
 }
 
 // SplitRegion is an OpStep that splits a region.
@@ -428,7 +428,7 @@ func (sr SplitRegion) CheckInProgress(_ ClusterInformer, _ *core.RegionInfo) err
 
 // Timeout returns true if the step is timeout.
 func (sr SplitRegion) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxFastWaitTime(regionSize)
+	return time.Since(start) > fastStepWaitDuration(regionSize)
 }
 
 // DemoteVoter is very similar to DemoteFollower. But it allows Demote Leader.
@@ -460,7 +460,7 @@ func (dv DemoteVoter) IsFinish(region *core.RegionInfo) bool {
 
 // Timeout returns true if the step is timeout.
 func (dv DemoteVoter) Timeout(start time.Time, regionSize int64) bool {
-	return time.Since(start) > maxFastWaitTime(regionSize)
+	return time.Since(start) > fastStepWaitDuration(regionSize)
 }
 
 // ChangePeerV2Enter is an OpStep that uses joint consensus to request all PromoteLearner and DemoteVoter.
@@ -607,7 +607,7 @@ func (cpe ChangePeerV2Enter) GetRequest() *pdpb.ChangePeerV2 {
 // Timeout returns true if the step is timeout.
 func (cpe ChangePeerV2Enter) Timeout(start time.Time, regionSize int64) bool {
 	count := uint64(len(cpe.PromoteLearners)+len(cpe.DemoteVoters)) + 1
-	return time.Since(start) > maxFastWaitTime(regionSize)*time.Duration(count)
+	return time.Since(start) > fastStepWaitDuration(regionSize)*time.Duration(count)
 }
 
 // ChangePeerV2Leave is an OpStep that leaves the joint state.
@@ -732,7 +732,7 @@ func (cpl ChangePeerV2Leave) Influence(_ OpInfluence, _ *core.RegionInfo) {}
 // Timeout returns true if the step is timeout.
 func (cpl ChangePeerV2Leave) Timeout(start time.Time, regionSize int64) bool {
 	count := uint64(len(cpl.PromoteLearners)+len(cpl.DemoteVoters)) + 1
-	return time.Since(start) > maxFastWaitTime(regionSize)*time.Duration(count)
+	return time.Since(start) > fastStepWaitDuration(regionSize)*time.Duration(count)
 }
 
 func validateStore(ci ClusterInformer, id uint64) error {
@@ -746,7 +746,7 @@ func validateStore(ci ClusterInformer, id uint64) error {
 	return nil
 }
 
-func maxSlowWaitTime(regionSize int64) time.Duration {
+func slowStepWaitDuration(regionSize int64) time.Duration {
 	seconds := DefaultSlowExecutorRate * regionSize
 	wait := time.Duration(seconds) * time.Second
 	if wait < SlowOperatorWaitTime {
@@ -755,7 +755,7 @@ func maxSlowWaitTime(regionSize int64) time.Duration {
 	return wait
 }
 
-func maxFastWaitTime(regionSize int64) time.Duration {
+func fastStepWaitDuration(regionSize int64) time.Duration {
 	seconds := int64(DefaultFastExecutorRate * float64(regionSize))
 	wait := time.Duration(seconds) * time.Second
 	if wait < FastOperatorWaitTime {