<form action="sql.aspx" method="post" enctype="multipart/form-data">
<input id="Text1" name="content" type="text" /><br />
<input id="Text2" name="uploadImg" type="text" /><br />
<input id="File1" type="file" name="image0" /><br />
<input id="Submit1" type="submit" value="submit" />
</form>

public string POSTfile(string v1,string v2, string file)
{
string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");

//請求
WebRequest req = WebRequest.Create(@"http://localhost.:4944/WebSite1/getfile.aspx");
req.Method = "POST";
req.ContentType = "multipart/form-data; boundary=" + boundary;

//組織表單數(shù)據(jù)
StringBuilder sb = new StringBuilder();
sb.Append("--" + boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"content\"");
sb.Append("\r\n\r\n");
sb.Append(v1);
sb.Append("\r\n");

sb.Append("--" + boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"uploadImg\"");
sb.Append("\r\n\r\n");
sb.Append("v2");
sb.Append("\r\n");

sb.Append("--" + boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"image0\"; filename=\"e:\\a.jpg\"");
sb.Append("\r\n");
sb.Append("Content-Type: image/pjpeg");
sb.Append("\r\n\r\n");

string head = sb.ToString();
byte[] form_data = Encoding.UTF8.GetBytes(head);
//結尾
byte[] foot_data = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");

//文件
FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
//post總長度
long length = form_data.Length + fileStream.Length + foot_data.Length;
req.ContentLength = length;

Stream requestStream = req.GetRequestStream();
//發(fā)送表單參數(shù)
requestStream.Write(form_data, 0, form_data.Length);
//文件內容
byte[] buffer = new Byte[checked((uint)Math.Min(4096, (int)fileStream.Length))];
int bytesRead = 0;
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
requestStream.Write(buffer, 0, bytesRead);
//結尾
requestStream.Write(foot_data, 0, foot_data.Length);
requestStream.Close();

//響應
WebResponse pos = req.GetResponse();
StreamReader sr = new StreamReader(pos.GetResponseStream(), Encoding.UTF8);
string html = sr.ReadToEnd().Trim();
sr.Close();
if (pos != null)
{
pos.Close();
pos = null;
}
if (req != null)
{
req = null;
}
return html;
}