<ul id="aaa">
<li style="float:left; height:500px; background:#F00;">1</li>
<li style="float:left; height:200px; background:#0F0;">2</li>
<li style="float:left; height:300px; background:#00F;">3</li>
</ul>
li {
width: 100px
}
$(document).ready(function() {
var max_h = 0;
$("#aaa li").each(function() {
var h = parseInt($(this).css("height"));
if (max_h < h) {
max_h = h;
}
});
$("#aaa li").each(function() {
$(this).css({
height: max_h
});
});
});