diff --git a/pkg/compute/models/snapshots.go b/pkg/compute/models/snapshots.go
index e78a91bd1b..ea57780729 100644
--- a/pkg/compute/models/snapshots.go
+++ b/pkg/compute/models/snapshots.go
@@ -9,7 +9,6 @@ import (
 	"yunion.io/x/jsonutils"
 	"yunion.io/x/log"
 	"yunion.io/x/pkg/util/compare"
-	"yunion.io/x/pkg/utils"
 	"yunion.io/x/sqlchemy"
 
 	"yunion.io/x/onecloud/pkg/cloudcommon/db"
@@ -348,29 +347,20 @@ func (self *SSnapshot) CustomizeDelete(ctx context.Context, userCred mcclient.To
 	if self.Status == SNAPSHOT_DELETING {
 		return fmt.Errorf("Cannot delete snapshot in status %s", self.Status)
 	}
-	if self.Status == SNAPSHOT_UNKNOWN {
-		return self.RealDelete(ctx, userCred)
-	}
 	if len(self.ExternalId) == 0 {
-		if utils.IsInStringArray(self.Status, []string{SNAPSHOT_FAILED}) {
-			return self.RealDelete(ctx, userCred)
-		}
 		if self.CreatedBy == MANUAL {
 			if !self.FakeDeleted {
 				return self.FakeDelete()
-			} else {
-				_, err := SnapshotManager.GetConvertSnapshot(self)
-				if err != nil {
-					return fmt.Errorf("Cannot delete snapshot: %s, disk need at least one of snapshot as backing file", err.Error())
-				}
-				return self.StartSnapshotDeleteTask(ctx, userCred, false, "")
 			}
-		} else {
-			return fmt.Errorf("Cannot delete snapshot created by %s", self.CreatedBy)
+			_, err := SnapshotManager.GetConvertSnapshot(self)
+			if err != nil {
+				return fmt.Errorf("Cannot delete snapshot: %s, disk need at least one of snapshot as backing file", err.Error())
+			}
+			return self.StartSnapshotDeleteTask(ctx, userCred, false, "")
 		}
-	} else {
-		return self.StartSnapshotDeleteTask(ctx, userCred, false, "")
+		return fmt.Errorf("Cannot delete snapshot created by %s", self.CreatedBy)
 	}
+	return self.StartSnapshotDeleteTask(ctx, userCred, false, "")
 }
 
 func (self *SSnapshot) AllowPerformDeleted(ctx context.Context, userCred mcclient.TokenCredential, query jsonutils.JSONObject, data jsonutils.JSONObject) bool {
diff --git a/pkg/compute/tasks/guest_disk_snapshot_task.go b/pkg/compute/tasks/guest_disk_snapshot_task.go
index 2c61be664e..da7f7d5cd6 100644
--- a/pkg/compute/tasks/guest_disk_snapshot_task.go
+++ b/pkg/compute/tasks/guest_disk_snapshot_task.go
@@ -162,12 +162,16 @@ func (self *SnapshotDeleteTask) deleteExternalSnapshot(ctx context.Context, snap
 	}
 	cloudSnapshot, err := cloudRegion.GetISnapshotById(snapshot.ExternalId)
 	if err != nil {
+		if err == cloudprovider.ErrNotFound {
+			return nil
+		}
 		log.Errorln(err, cloudSnapshot)
 		return err
 	}
-	cloudSnapshot.Delete()
-	err = cloudprovider.WaitDeleted(cloudSnapshot, 10*time.Second, 300*time.Second)
-	return err
+	if err := cloudSnapshot.Delete(); err != nil {
+		return err
+	}
+	return cloudprovider.WaitDeleted(cloudSnapshot, 10*time.Second, 300*time.Second)
 }
 
 func (self *SnapshotDeleteTask) StartReloadDisk(ctx context.Context, snapshot *models.SSnapshot, guest *models.SGuest) {
diff --git a/pkg/util/aliyun/snapshot.go b/pkg/util/aliyun/snapshot.go
index e19ace3e3c..e087e3a673 100644
--- a/pkg/util/aliyun/snapshot.go
+++ b/pkg/util/aliyun/snapshot.go
@@ -160,13 +160,16 @@ func (self *SRegion) GetSnapshots(instanceId string, diskId string, snapshotName
 }
 
 func (self *SRegion) GetISnapshotById(snapshotId string) (cloudprovider.ICloudSnapshot, error) {
-	if snapshots, total, err := self.GetSnapshots("", "", "", []string{snapshotId}, 0, 1); err != nil {
+	snapshots, total, err := self.GetSnapshots("", "", "", []string{snapshotId}, 0, 1)
+	if err != nil {
 		return nil, err
-	} else if total != 1 {
-		return nil, cloudprovider.ErrNotFound
-	} else {
-		return &snapshots[0], nil
 	}
+	if total == 0 {
+		return nil, cloudprovider.ErrNotFound
+	} else if total > 1 {
+		return nil, cloudprovider.ErrDuplicateId
+	}
+	return &snapshots[0], nil
 }
 
 func (self *SRegion) DeleteSnapshot(snapshotId string) error {