如何获取文件的MD5，来这里看看

两步搞定

1、引用
using System.Security.Cryptography;
using System.IO;

2、复制下面的方法。

 private static string GetFileMD5(string fileName)
        {
            try
            {
                var file = new FileStream(fileName, FileMode.Open);
                var md5 = new MD5CryptoServiceProvider();
                var retVal = md5.ComputeHash(file);
                file.Close();
                var sb = new StringBuilder();
                for (var i = 0; i < retVal.Length; i++)
                {
                    sb.Append(retVal[i].ToString("x2"));
                }
                return sb.ToString();
            }
            catch (Exception)
            {
                return string.Empty;
            }
        }