diff --git a/apps/terminal/serializers/terminal.py b/apps/terminal/serializers/terminal.py
index aee43e833..25b72ab2c 100644
--- a/apps/terminal/serializers/terminal.py
+++ b/apps/terminal/serializers/terminal.py
@@ -32,7 +32,7 @@ class StatusSerializer(serializers.ModelSerializer):
 
 
 class TerminalSerializer(BulkModelSerializer):
-    session_online = serializers.SerializerMethodField()
+    session_online = serializers.ReadOnlyField(source='get_online_session_count')
     is_alive = serializers.BooleanField(read_only=True)
     status = serializers.CharField(read_only=True, source='latest_status')
     status_display = serializers.CharField(read_only=True, source='latest_status_display')
@@ -73,10 +73,6 @@ class TerminalSerializer(BulkModelSerializer):
         else:
             raise serializers.ValidationError(_('Not found'))
 
-    @staticmethod
-    def get_session_online(obj):
-        return Session.objects.filter(terminal=obj, is_finished=False).count()
-
 
 class TaskSerializer(BulkModelSerializer):
     class Meta: