<span class="up-btn" id="selectFile">請選擇文件</span>
<input type="file" name="fileupload" style="FILTER: alpha(opacity=0); moz-opacity: 0; opacity: 0;" />

jQuery('#selectFile').live('click',function(){
  var ie = !-[1,];
  if(ie){
   jQuery('input:file').trigger('click').trigger('change');
  }else{
   jQuery('input:file').trigger('click');
  }

 });

 jQuery('input:file').change(function(){
  //dosomthing
 });