<!DOCTYPE html>
<html>

  <head>
    <meta charset="UTF-8">
    <title>jQuery取消checkbox选中状态</title>
  </head>

  <body>
    <input type="button" value="取消" onclick="box();" />
    
    <input type="checkbox" checked="checked" id="box" />
  </body>
  <script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
  <script>
    function box() { 
      $("#box").attr("checked", false); 
    }
  </script>

</html>