Use Label for Tree labelField
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Tree labelField="label" width="200"> <mx:ArrayCollection> <mx:Array> <mx:Object label="A"> <mx:children> <mx:Object label="A1" /> <mx:Object label="A2" /> </mx:children> </mx:Object> <mx:Object label="B"> <mx:children> <mx:Object label="B1" /> </mx:children> </mx:Object> </mx:Array> </mx:ArrayCollection> </mx:Tree> </mx:Application>