问题出现了我们需要解决，解决方案如下：

1、运行下regsvr32 msxml3.dll；
2、用现成的框架来做ajax；
3、代码优化：

if(window.ActiveXObject)
    {
        xmlHttp = new ActiveXObject(Microsoft.XMLHTTP);
    }
    else if(window.XMLHttpRequest)
    {
        xmlHttp = new XMLHttpRequest();
    }

    if(handle_s == null)
        handle_s = bin/normal.py/db;
    this.xmlHttp.onreadystatechange = handle_l;
    this.xmlHttp.open(GET,handle_s,true);
    this.xmlHttp.send(null);

或判断浏览器

var agt = navigator.userAgent.toLowerCase();
var is_ie = (agt.indexOf(msie) != -1);
var is_ie5 = (agt.indexOf(msie 5) != -1);
var is_opera = (agt.indexOf(opera) != -1);
var is_mac = (agt.indexOf(mac) != -1);
var is_gecko = (agt.indexOf(gecko) != -1);
var is_safari = (agt.indexOf(safari) != -1);

function CreateXmlHttpReq(handler) {

var xmlhttp = null;
if (is_ie) {
// Guaranteed to be ie5 or ie6
var control = (is_ie5) ? Microsoft.XMLHTTP : Msxml2.XMLHTTP;

try {
xmlhttp = new ActiveXObject(control);
xmlhttp.onreadystatechange = handler;
} catch (ex) {
// TODO: better help message
alert(You need to enable active scripting and activeX controls);
}

} else {

// Mozilla
xmlhttp = new XMLHttpRequest();
xmlhttp.onload = handler;
xmlhttp.onerror = handler;

}

return xmlhttp;
}

或者

<script language=javascript>
    var http_request = false;
    function send_request(url) {//初始化、指定处理函数、发送请求的函数
        http_request = false;
        //开始初始化XMLHttpRequest对象
        if(window.XMLHttpRequest) { //Mozilla 浏览器
            http_request = new XMLHttpRequest();
            if (http_request.overrideMimeType) {//设置MiME类别
                http_request.overrideMimeType(text/xml);
            }
        }
        else if (window.ActiveXObject) { // IE浏览器
            try {
                http_request = new ActiveXObject(Msxml2.XMLHTTP);
            } catch (e) {
                try {
                    http_request = new ActiveXObject(Microsoft.XMLHTTP);
                } catch (e) {}
            }
        }
        if (!http_request) { // 异常，创建对象实例失败
            window.alert(不能创建XMLHttpRequest对象实例.);
            return false;
        }
        http_request.onreadystatechange = processRequest;
        // 确定发送请求的方式和URL以及是否同步执行下段代码
        http_request.open(GET, url, true);
        http_request.send(null);
    }
    // 处理返回信息的函数
    function processRequest() {
        if (http_request.readyState == 4) { // 判断对象状态
            if (http_request.status == 200) { // 信息已经成功返回，开始处理信息
                var returnObj = http_request.responseXML;
                var xmlobj = http_request.responseXML;
                var employees = xmlobj.getElementsByTagName(employee);
                var feedbackStr = ;
                for(var i=0;i<employees.length;i++) { // 循环读取employees.xml的内容
                    var employee = employees[i];
                    feedbackStr += 员工： + employee.getAttribute(name);//取得标签指定属性
                    feedbackStr += 职位： + employee.getElementsByTagName(job)[0].firstChild.data;//取得指定标签的最初数据
                    feedbackStr += 工资： + employee.getElementsByTagName(salary)[0].firstChild.data;
                    feedbackStr +=  \r\n;
                }
                alert(feedbackStr);
            } else { //页面不正常
                alert(您所请求的页面有异常。);
            }
        }
    }
</script>
http://www.cnblogs.com/skylaugh/archive/2006/11/20/566164.html