自己解决了，这接口传递的时间是utc时间，而我传递的是local的时间所以没取到；结贴

使用HttpWebRequest 发送请求成功，代码如下 HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;                 CookieContainer cookieContainer = new CookieContainer();                 request.CookieContainer = cookieContainer;                 request.AllowAutoRedirect = true;                 request.Method = "POST";                 string boundary = DateTime.Now.Ticks.ToString("X");                 request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;                 byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");                 byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");                 int pos = path.LastIndexOf("\\");                 string fileName = path.Substring(pos + 1);                 StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"" + formName + "\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", fileName));                 byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString());                 FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);                 byte[] bArr = new byte[fs.Length];                 fs.Read(bArr, 0, bArr.Length);                 fs.Close();                 Stream postStream = request.GetRequestStream();                 postStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);                 postStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);                 postStream.Write(bArr, 0, bArr.Length);                 byte[] bSplit = Encoding.UTF8.GetBytes("--" + boundary + "\r\n");                 postStream.Write(bSplit, 0, bSplit.Length);                 if (!string.IsNullOrEmpty(additionInfo))                 {                     byte[] additionBytes = Encoding.UTF8.GetBytes("Content-Disposition: form-data; name=\"description\";\r\n\r\n");                     postStream.Write(additionBytes, 0, additionBytes.Length);                     byte[] additionContentBytes = Encoding.UTF8.GetBytes(additionInfo);                     postStream.Write(additionContentBytes, 0, additionContentBytes.Length);                     postStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);                 }                 postStream.Close();                 HttpWebResponse response = request.GetResponse() as HttpWebResponse;                 Stream instream = response.GetResponseStream();                 StreamReader sr = new StreamReader(instream, Encoding.UTF8);                 content = sr.ReadToEnd(); 但是使用HttpClient就一直提示41005，代码如下             using (var client = _clientFactory.CreateClient())             {                 var file = new FileInfo(filePath);     byte[] buffur = File.ReadAllBytes(filePath);                 using (var formData = new MultipartFormDataContent())                 {                     ByteArrayContent fileContent = new ByteArrayContent(buffur);     fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data") { Name = formName, FileName = file.Name };     formData.Add(fileContent);                     var response = await client.PostAsync(url, formData);                     if (response.IsSuccessStatusCode)                     {                         var result = await response.Content.ReadAsStringAsync();                         return result;                     }                     else                     {                         throw new BadHttpResponseException(url, response.StatusCode);                     }                 }             } 对比了一下貌似区别在换行符上"\r\n",但是封装好的HttpClient又不知道如何添加相应的换行符。 不知道这个是不是根本原因。