var my_loader:Loader = new Loader();
my_loader.load(new URLRequest("swf1.swf"));
my_loader.contentLoaderInfo.addEventListener(Event.INIT, initHandler);
my_loader.contentLoaderInfo.addEventListener(Event.COMPLETE, _SHOW);

function initHandler(event:Event):void {
    var loader:Loader = Loader(event.target.loader);
    var info:LoaderInfo = LoaderInfo(loader.contentLoaderInfo);
    trace(info.frameRate);
    stage.frameRate = info.frameRate;
    addChild(loader);
}
function _SHOW(e:Event):void {
   
}

//获取被加载SWF的帧频用:
var info:LoaderInfo = LoaderInfo(loader.contentLoaderInfo);
trace(info.frameRate);
//将被加载SWF的帧频赋值给主影片的帧频。
stage.frameRate = info.frameRate;

//动态改变帧频。
stage.frameRate =24