SOURCE

function UploadFile(id，url) {
//id 表单ID
  $.ajax({
    url: url,
    type: 'POST',
    data: new FormData($("#"+id)[0]),
    async: false,
    cache: false,
    contentType: false,
    processData: false,
    success: function(returndata) {
      alert(returndata);
    },
    error: function(returndata) {
      alert(returndata);
    }
  });
}

<div>
  Hello World
</div>
        <form method="post" enctype="multipart/form-data" action="/api/Project/UploadMedia">
            <div class="form-group">
                <label for="ProjectName">项目名</label>
                <input type="text" class="form-control" name="ProjectName" id="ProjectName" placeholder="项目名">
            </div>
            <div class="form-group">
                <label for="UpdateTime">更新时间</label>
                <input type="date" class="form-control" name="UpdateTime" id="UpdateTime" placeholder="更新时间">
            </div>
            <div class="form-group">
                <label for="exampleInputFile">上传的文件</label>
                <input type="file" name="FileData" id="exampleInputFile">
                <p class="help-block">选择要上传的文件</p>
            </div>
            <button type="submit" class="btn btn-default">提交</button>
        </form>