ممنون دوست عزیز با کد زیر مشکلم حل شد
var zoom:Number = 5;
stage.addEventListener(MouseEvent.MOUSE_WHEEL,WH,f alse,0,true);
function WH(e:MouseEvent):void
{
trace(e.delta); // this is the amount which each 'click' of the mouse wheel creates
pic.z=pic.z + e.delta * zoom;

}