参考代码：

//企业类别级联
function getCatalog(){
var name=document.getElementById("Lcata").value;
var selectObj=document.getElementById("scata");
selectObj.options.length =0;

  $.ajax({  
        type:"POST",  
        url: "/YHPC/getCata.action?name="+name+"&random="+Math.random()+"&way=ajax",//获取数据的函数  
        dataType:"xml",  
        async:false,  
        dataFilter:function(e){  
          if(e=='sessionOut'){  
              location.href="login.jsp";  
              return false;  
          }  
          var obj= eval(e);  
          selectObj.removeAttribute("Option");  
          for(var i=0;i<obj.length;i++){  
             selectObj.options\[selectObj.length\] = new Option(obj\[i\]\[1\], obj\[i\]\[0\]);  
          }

        }  
 });

}