<style type="text/css">
    #loading{position:fixed;_position:absolute;top:50%;left:50%;width:120px;height:120px;overflow:hidden;background:url(images/loading.gif) no-repeat;z-index:10;display:none;}
</style>

<div id="loading"></div>

<script type="text/javascript">
    $(document).ready(function () {
        $("#loading").show();//显示loading
        setTimeout("$('#loading').hide();", 5000);//隐藏loading
    });
</script>