直接上代码如下：

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
            FtpHelper ftpHelper = new FtpHelper("xxxxx", "","Administrator","1qaz@qwer");
            string[] datas = ftpHelper.GetAllList(null);
            Console.WriteLine(JsonConvert.SerializeObject(datas));
            Console.ReadLine();
        } 
    }


    public class FtpHelper
    {
        string ftpServerIP;
        string ftpRemotePath;
        string ftpUserID;
        string ftpPassword;
        string ftpURI;

        /// <summary>
        /// 连接FTP
        /// </summary>
        /// <param name="FtpServerIP">FTP连接地址</param>
        /// <param name="FtpRemotePath">指定FTP连接成功后的当前目录, 如果不指定即默认为根目录</param>
        /// <param name="FtpUserID">用户名</param>
        /// <param name="FtpPassword">密码</param>
        public FtpHelper(string FtpServerIP, string FtpRemotePath, string FtpUserID, string FtpPassword)
        {
            ftpServerIP = FtpServerIP;
            ftpRemotePath = FtpRemotePath;
            ftpUserID = FtpUserID;
            ftpPassword = FtpPassword;
            if (string.IsNullOrEmpty(ftpRemotePath))
            {
                ftpURI = "ftp://" + ftpServerIP + "/";
            }
            else
            {
                ftpURI = "ftp://" + ftpServerIP + "/" + ftpRemotePath + "/";
            }
            
        }


        /// <summary>
        /// 下载
        /// </summary>
        /// <param name="filePath">下载保存的文件夹路径</param>
        /// <param name="fileName">文件名称</param>
        public bool Download(string filePath, string fileName)
        {
            try
            {
                FileStream outputStream = new FileStream(filePath + "\\" + fileName, FileMode.Create);
                FtpWebRequest reqFTP;
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + fileName));
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
                reqFTP.UseBinary = true;
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                Stream ftpStream = response.GetResponseStream();
                long cl = response.ContentLength;
                int bufferSize = 2048;
                int readCount;
                byte[] buffer = new byte[bufferSize];
                readCount = ftpStream.Read(buffer, 0, bufferSize);
                while (readCount > 0)
                {
                    outputStream.Write(buffer, 0, readCount);
                    readCount = ftpStream.Read(buffer, 0, bufferSize);
                }
                ftpStream.Close();
                outputStream.Close();
                response.Close();
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }

        /// <summary>
        /// 下载的异步方法
        /// </summary>
        /// <param name="filePath">下载保存的文件夹路径</param>
        /// <param name="fileName">文件名称</param>
        /// <returns></returns>
        public Task<bool> DownloadAsync(string filePath, string fileName)
        {
            return Task.Run(() => { return Download(filePath, fileName); });
        }

        /// <summary>
        /// 获取文件名称
        /// </summary>
        /// <param name="url">为空则获取根目录下所有</param>
        /// <returns></returns>
        public string[] GetAllList(string url)
        {
            List<string> list = new List<string>();
            FtpWebRequest req = (FtpWebRequest)WebRequest.Create(new Uri(ftpURI));
            req.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
            req.Method = WebRequestMethods.Ftp.ListDirectory;
            req.UseBinary = true;
            req.UsePassive = true;
            try
            {
                using (FtpWebResponse res = (FtpWebResponse)req.GetResponse())
                {
                    using (StreamReader sr = new StreamReader(res.GetResponseStream()))
                    {
                        string s;
                        while ((s = sr.ReadLine()) != null)
                        {
                            list.Add(s);
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.StackTrace);
            }
            return list.ToArray();
        }



        /// <summary>  
        /// 获取当前目录下明细(包含文件和文件夹)  
        /// </summary>  
        public string[] GetFilesDetailList()
        {
            try
            {
                StringBuilder result = new StringBuilder();
                FtpWebRequest ftp;
                ftp = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI));
                ftp.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                ftp.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
                WebResponse response = ftp.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream());
                string line = reader.ReadLine();
                line = reader.ReadLine();
                line = reader.ReadLine();
                while (line != null)
                {
                    result.Append(line);
                    result.Append("\n");
                    line = reader.ReadLine();
                }
                result.Remove(result.ToString().LastIndexOf("\n"), 1);
                reader.Close();
                response.Close();
                return result.ToString().Split('\n');
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
        }


        /// <summary>  
        /// 移动文件  
        /// </summary>  
        public void MovieFile(string currentFilename, string newDirectory)
        {
            ReName(currentFilename, newDirectory);
        }
        /// <summary>  
        /// 更改文件名  
        /// </summary> 
        public bool ReName(string currentFilename, string newFilename)
        {
            FtpWebRequest reqFTP;
            try
            {
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + currentFilename));
                reqFTP.Method = WebRequestMethods.Ftp.Rename;
                reqFTP.RenameTo = newFilename;
                reqFTP.UseBinary = true;
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                Stream ftpStream = response.GetResponseStream();
                ftpStream.Close();
                response.Close();
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }
        /// <summary>  
        /// 获取指定文件大小  
        /// </summary>  
        public long GetFileSize(string filename)
        {
            FtpWebRequest reqFTP;
            long fileSize = 0;
            try
            {
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + filename));
                reqFTP.Method = WebRequestMethods.Ftp.GetFileSize;
                reqFTP.UseBinary = true;
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                Stream ftpStream = response.GetResponseStream();
                fileSize = response.ContentLength;
                ftpStream.Close();
                response.Close();
            }
            catch (Exception ex)
            {

            }
            return fileSize;
        }
        /// <summary>  
        /// 创建文件夹  
        /// </summary>   
        public bool MakeDir(string dirName)
        {
            FtpWebRequest reqFTP;
            try
            {
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + dirName));
                reqFTP.Method = WebRequestMethods.Ftp.MakeDirectory;
                reqFTP.UseBinary = true;
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                Stream ftpStream = response.GetResponseStream();
                ftpStream.Close();
                response.Close();
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }

        /// <summary>  
        /// 删除文件  
        /// </summary>  
        public bool Delete(string fileName)
        {
            try
            {
                FtpWebRequest reqFTP;
                reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + fileName));
                reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                reqFTP.Method = WebRequestMethods.Ftp.DeleteFile;
                reqFTP.KeepAlive = false;
                string result = String.Empty;
                FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                long size = response.ContentLength;
                Stream datastream = response.GetResponseStream();
                StreamReader sr = new StreamReader(datastream);
                result = sr.ReadToEnd();
                sr.Close();
                datastream.Close();
                response.Close();
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }

        /// <summary>  
        /// 上传  
        /// </summary>   
        public bool Upload(string filename)
        {
            FileInfo fileInf = new FileInfo(filename);
            FtpWebRequest reqFTP;
            reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpURI + fileInf.Name));
            reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
            reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
            reqFTP.KeepAlive = false;
            reqFTP.UseBinary = true;
            reqFTP.ContentLength = fileInf.Length;
            int buffLength = 2048;
            byte[] buff = new byte[buffLength];
            int contentLen;
            FileStream fs = fileInf.OpenRead();
            try
            {
                Stream strm = reqFTP.GetRequestStream();
                contentLen = fs.Read(buff, 0, buffLength);
                while (contentLen != 0)
                {
                    strm.Write(buff, 0, contentLen);
                    contentLen = fs.Read(buff, 0, buffLength);
                }
                strm.Close();
                fs.Close();
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
        }

        /// <summary>
        /// 上传的异步方法
        /// </summary>
        /// <param name="filename"></param>
        /// <returns></returns>
        public Task<bool> UploadAsync(string filename)
        {
            return Task.Run(() => { return Upload(filename); });
        }
    }
}