function IsInstallQQ()
{
    try
    {
        var xmlhttp=new ActiveXObject("TimwpDll.TimwpCheck");
        return true;
    }
    catch(e)
    {
        return false;
    }
    return false;
}
function LoadQQ(qq,webSiteName,webUrl)
{
    var boolFals=IsInstallQQ();
    if(boolFals==true)
    { 
        if(undefined==qq || null==qq || ""==qq) qq="372815415";
        if(undefined==webSiteName || null==webSiteName || ""==webSiteName) webSiteName="明道";
        if(undefined==webUrl || null== webUrl || ""==webUrl) webUrl="http://www.mdbq.com";
        location.href="Tencent://Message/?menu=yes&exe=&uin="+qq+"&websiteName="+webSiteName+","+webUrl+"&info=";
    }
    else
    {
        location.href='http://is.qq.com/webpresence/up_alarm.shtml';
    }
}

------解决方案--------------------
好像有个类似于mailto:的标签，是qq:

------解决方案--------------------
学习了。