Try this code,
<html>
<head>
<!-- Include your local jQuery<version>.js here-->
<script src="..\jquery-1.3.2.js"></script>
<script>
function getChildLength(){
var divArr = $('div');
var childLength = $(divArr[0]).children().length;
alert("Length :::"+ childLength );
}
</script>
</head>
<body onload="getChildLength();">
<div>
<span> HI </span>
<span> Hello </span>
</div>
<div>
<a href="http://show.zoho.com"> ZohoShow</a>
</div>
</body>
</html>
Result : Length - 2