diff --git a/consensus/ibft/ibft.go b/consensus/ibft/ibft.go
index 9ec8587a58..384c6deb97 100644
--- a/consensus/ibft/ibft.go
+++ b/consensus/ibft/ibft.go
@@ -544,8 +544,8 @@ func (i *Ibft) startConsensus() {
 
 		isValidator = i.isValidSnapshot()
 
-		if isValidator {
-			// i.startNewSequence()
+		// validator must not be in syncing mode to start a new block
+		if isValidator && !i.syncer.IsSyncing() {
 			sequenceCh = i.runSequence(pending)
 		}
 
diff --git a/protocol/interface.go b/protocol/interface.go
index 9ee6c71f02..23826287a0 100644
--- a/protocol/interface.go
+++ b/protocol/interface.go
@@ -21,6 +21,8 @@ type Syncer interface {
 	GetSyncProgression() *progress.Progression
 	// HasSyncPeer returns whether syncer has the peer syncer can sync with
 	HasSyncPeer() bool
+	// IsSyncing returns whether syncer is syncing
+	IsSyncing() bool
 	// Sync starts routine to sync blocks
 	Sync(func(*types.Block) bool) error
 }
diff --git a/protocol/syncer.go b/protocol/syncer.go
index 4681c674f9..513acbf837 100644
--- a/protocol/syncer.go
+++ b/protocol/syncer.go
@@ -136,12 +136,16 @@ func NewSyncer(
 	return s
 }
 
-func (s *noForkSyncer) isSyncing() bool {
+func (s *noForkSyncer) IsSyncing() bool {
 	return s.syncing.Load()
 }
 
-func (s *noForkSyncer) setSyncing(syncing bool) (oldStatus bool) {
-	return s.syncing.Swap(syncing)
+func (s *noForkSyncer) startSyncingStatus() (success bool) {
+	return s.syncing.CompareAndSwap(false, true)
+}
+
+func (s *noForkSyncer) stopSyncingStatus() (success bool) {
+	return s.syncing.CompareAndSwap(true, false)
 }
 
 // GetSyncProgression returns the latest sync progression, if any
@@ -300,15 +304,13 @@ func (s *noForkSyncer) Sync(callback func(*types.Block) bool) error {
 			}
 
 			// The channel should not be blocked, otherwise it will hang when an error occurs
-			if s.isSyncing() {
+			if !s.startSyncingStatus() {
 				s.logger.Debug("skip new status event due to not done syncing")
 
 				continue
 			}
 		}
 
-		s.logger.Debug("got new status event")
-
 		if shouldTerminate := s.syncWithSkipList(skipList, callback); shouldTerminate {
 			s.logger.Error("terminate syncing")
 
@@ -323,12 +325,13 @@ func (s *noForkSyncer) syncWithSkipList(
 	skipList *sync.Map,
 	callback func(*types.Block) bool,
 ) (shouldTerminate bool) {
-	// switch syncing status
-	s.setSyncing(true)
-	defer s.setSyncing(false)
+	s.logger.Debug("got new status event and start syncing")
 
-	s.logger.Debug("start syncing")
-	defer s.logger.Debug("done syncing")
+	// switch syncing status
+	defer func() {
+		s.logger.Debug("done syncing")
+		s.stopSyncingStatus()
+	}()
 
 	var localLatest uint64
 
diff --git a/protocol/syncer_test.go b/protocol/syncer_test.go
index 8629061f33..52b8bda125 100644
--- a/protocol/syncer_test.go
+++ b/protocol/syncer_test.go
@@ -212,7 +212,7 @@ func Test_startPeerStatusUpdateProcess(t *testing.T) {
 		&mockProgression{},
 	)
 
-	syncer.setSyncing(true) // to skip channel blocking
+	syncer.startSyncingStatus() // to skip channel blocking
 
 	go syncer.Sync(nil)