<script type="text/javascript">
  $(function() {
      $("#btnSet").click(function() {
        var a = $("#txtValue").val();
        var data = { Name: a };
        alert(data);
        $.ajax({
          url: '@Url.Action("MyTest")',
          type: 'post',
          dataType: 'json',
          data: data,
        });
      });
    }
  );
</script>
<h2>Index</h2>
<input type="text" id="txtValue"/><input type="button" value="设置" id="btnSet"/>

  public ActionResult MyTest(StudentInfo stu)
    {
      return Content("OK");
    }

  public class StudentInfo
  {
    public string Name { get; set; }
  }

<script type="text/javascript">
  $(function() {
      $("#btnSet").click(function() {
        var a = $("#txtValue").val();
        var data = JSON.stringify({ Name: a });
        alert(data);
        $.ajax({
          url: '@Url.Action("MyTest")',
          type: 'post',
          dataType: 'json',
          data: data,
          contentType: 'application/json'
        });
      });
    }
  );
</script>