// Add your javascript here
$('document').ready(function(){

$(".accordion-dropdpwn").on('change', function(e){
    var selected_value = $(this).val(),
        $target_elem = $('a[href="' + selected_value + '"]');
       $target_elem.trigger('click');
        

});

$('.accordion-toggle').on('click', function(){
     var selected_value = $(this).attr('href');
     $(".accordion-dropdown option").removeAttr('selected');
     $('option[value="' + selected_value + '"]').attr('selected', 'selected');
});

$(".accordion-toggle").trigger('change');

});
<!DOCTYPE html>
<! http://stackoverflow.com/questions/15231707/twitter-bootstrap-collapse-triggered-with-a-select >
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Bootstrap, from Twitter</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="">
    <meta name="author" content="">

    <!-- Le styles -->
    <link href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.2.1/css/bootstrap-combined.min.css" rel="stylesheet">
    <style>
      body {
        padding-top: 60px;
      }
      @media (max-width: 979px) {

        /* Remove any padding from the body */
        body {
          padding-top: 0;
        }
      }
    </style>
    <link href="style.css" rel="stylesheet">

    <!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
    <!--[if lt IE 9]>
      <script src="//html5shim.googlecode.com/svn/trunk/html5.js"></script>
    <![endif]-->

    <!-- Le fav and touch icons -->
    <link rel="shortcut icon" href="images/favicon.ico">
    <link rel="apple-touch-icon" href="images/apple-touch-icon.png">
    <link rel="apple-touch-icon" sizes="72x72" href="images/apple-touch-icon-72x72.png">
    <link rel="apple-touch-icon" sizes="114x114" href="images/apple-touch-icon-114x114.png">
  </head>

  <body>

  	  <select class="accordion-dropdpwn">
  	  <option selected="selected" value="#panel1" data-parent="#accordion">1</option>
  	  <option value="#panel2" data-parent="#accordion">2</option>
      <option value="#panel3" data-parent="#accordion">3</option>
      <option value="#panel4" data-parent="#accordion">4</option>
      <option value="#panel5" data-parent="#accordion">5</option>
  </select>
  

  <div class="accordion" id="accordion">
    <div class="accordion-group">
        <div class="accordion-heading">
            <a class="accordion-toggle" data-parent="#accordion" data-toggle="collapse" href="#panel1">Panel 1</a>
        </div>
        <div class="accordion-body collapse" id="panel1">
            <div class="accordion-inner">
                <p>This is accordion panel 1 content</p>
            </div>
        </div>
    </div>
    <div class="accordion-group">
        <div class="accordion-heading">
            <a class="accordion-toggle" data-parent="#accordion" data-toggle="collapse" href="#panel2">Panel 2</a>
        </div>
        <div class="accordion-body collapse" id="panel2">
            <div class="accordion-inner">
                <p>This is accordion panel 2 content</p>
            </div>
        </div>
    </div>
     <div class="accordion-group">
        <div class="accordion-heading">
            <a class="accordion-toggle" data-parent="#accordion" data-toggle="collapse" href="#panel3">Panel 3</a>
        </div>
        <div class="accordion-body collapse" id="panel3">
            <div class="accordion-inner">
                <p>This is accordion panel 3 content</p>
            </div>
        </div>
    </div>
     <div class="accordion-group">
        <div class="accordion-heading">
            <a class="accordion-toggle" data-parent="#accordion" data-toggle="collapse" href="#panel4">Panel 4</a>
        </div>
        <div class="accordion-body collapse" id="panel4">
            <div class="accordion-inner">
                <p>This is accordion panel 4 content</p>
            </div>
        </div>
    </div>
     <div class="accordion-group">
        <div class="accordion-heading">
            <a class="accordion-toggle" data-parent="#accordion" data-toggle="collapse" href="#panel5">Panel 5</a>
        </div>
        <div class="accordion-body collapse" id="panel5">
            <div class="accordion-inner">
                <p>This is accordion panel 5 content</p>
            </div>
        </div>
    </div>
</div>
    <!-- Le javascript
    ================================================== -->
    <!-- Placed at the end of the document so the pages load faster -->
    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
    <script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.2.1/js/bootstrap.min.js"></script>
    <script src="script.js"></script>
  </body>
</html>
/* Put your css in here */
.accordion-body {background: #f90;}