The below code snippet explains how to set selectedIndex of HTML Select Dropdown using jQuery
<select id="mySelect">
    <option value="1">Yes</option>
    <option value="2">No</option>
<input type="button" id="demo" value = "Demo" />
<script type = "text/javascript" src = ""></script>
<script type="text/javascript">
    $("#demo").live("click", function () {
        //Set the selectedIndex
        $("#mySelect")[0].selectedIndex = 1;
The button with ID demo is attached with a click event. When the button is clicked the selectedIndex of the HTML Select Dropdown with ID mySelect is set using jQuery