Edit in JSFiddle

$(function(){
  $("li").css("top", function(index){
    return index * 50;
  });
});
<ul>
  <li>hoge</li>
  <li>hoge</li>
  <li>hoge</li>
  <li>hoge</li>
  <li>hoge</li>
</ul>
li {
  position: absolute;
}