html 代码：

<script type="text/javascript" src="http://你的域名/js/jquery-1.4.2.min.js"></script>
 <script type="text/javascript"> 
$(function(){  
$.ajax(  
    {  
        type:'get',  
        url : 'http://你的域名/test.php?loginuser=lee&loginpass=123456',  
        dataType : 'jsonp',  
        jsonp:"jsoncallback",  
        success  : function(data) {  
            alert("用户名："+ data.user +" 密码："+ data.pass);  
        },  
        error : function() {  
            alert('fail');  
        }  
    }  
);  
}) 
</script> 


服务端 test.php
<?php  
header('Content-Type:text/html;Charset=utf-8');  
$arr = array(  
    "user" => $_GET['loginuser'],  
    "pass" => $_GET['loginpass'],  
    "name" => 'response'  
  
);  
echo $_GET['jsoncallback'] . "(".json_encode($arr).")";