<HTML>
<BODY>
<script>
function $(id){
  return document.getElementById(id)
}
function fillCity(){
  var Arr=[
    ['chengdu','mianyang','aba'],
    ['wuhan','jingzhou','yichang']
  ]
  for(var p=0,t;t=Arr[$('p').value][p++];){
    var o = new Option
    o.value= p
    o.text = t
    $('c').add(o)
 }
}
</script>
选择省份:<select id="p" onChange="javascript:fillCity()">
      <option></option>
      <option value="0">省份1</option>
      <option value="1">省份2</option></select>
<hr>
选择城市:<select id="c" ></select>
</BODY>
</HTML>