<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'
src='http://code.jquery.com/jquery-1.10.1.js'></script>
<style type='text/css'>
#load {
position: fixed;
background: #EEE;
opacity: 0.5;
left: 22px;
top: 0px;
width: 100%;
height: 100%;
display: none;
}
</style>
<script type='text/javascript'>//<![CDATA[
$(window).load(function(){
$("form").submit(function(){
$("#load").show();
});
});//]]>
</script>
</head>
<body>
<form action="" method="post">
<input type="Submit" value="submit">
</form>
<div id="load">
<img src="http://www.w3cschool.cn/style/download.png" />
</div>
</body>
</html>