前端:

<!--<link href="~/assets/css/amazeui.min.css" rel="stylesheet" />-->
<!--<script src="~/assets/js/jquery.min.js"></script>-->
<div class="am-form-group am-form-file">
  <button type="button" class="am-btn am-btn-danger am-btn-sm">
    <i class="am-icon-cloud-upload"
 
></i> 選擇要上傳的檔案</button>
  <input id="doc-form-file" type="file" multiple>
</div>
<script>
      $('#doc-form-file').on('change', function () {
        var file = this.files[0];
        var fileName = file.name;
        var fileType = fileName.substr(fileName.length - 4, fileName.
 
length);
        if (fileType == '.docx' || fileType == '.doc') {
            var formData = new FormData()
            formData.append("file", file);
            $.ajax({
                url: '/Home/upLoadFile',
                type: 'POST',
                cache: false,
                data: formData,
 

                dataType: "json",
                processData: false,
                contentType: false,
                success: function (json) {
                    //上傳成功的處理
            });
        } else {
        alert('檔案型別不正確');
        }
    });
</script>

後臺：

        public ActionResult upLoadFile(HttpPostedFileBase file)
        {
                int fileContentLength = file.ContentLength;
                string filePath = Server.MapPath("~/檔案儲存目錄");
                byte[] fileBytes = new byte[fileContentLength];
                Stream fileStream = file.InputStream;
                fileStream.Read(fileBytes, 0, fileContentLength);
                string fullPath = filePath + System.IO.Path.GetFileName(file.FileName);
                SaveToDisk(fileBytes, fullPath);
        }
        public void SaveToDisk(byte[] bytes, string saveFullPath)
        {
            var fullPath = Path.GetDirectoryName(saveFullPath);
            //如果沒有此資料夾，則新建
            if (!Directory.Exists(fullPath))
            {
                Directory.CreateDirectory(fullPath);
            }
            //建立檔案，返回一個 FileStream，它提供對 path 中指定的檔案的讀/寫訪問。
            using (FileStream stream = System.IO.File.Create(saveFullPath))
            {
                //將位元組陣列寫入流
                stream.Write(bytes, 0, bytes.Length);
            }
        }