文章转自：https://www.cnblogs.com/hh8888-log/p/10687986.html
由于这位大佬贴的是图，我就把对应的代码整了整放上来了

using IWshRuntimeLibrary;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Windows.Forms;

namespace HCDCapp.Main
{
    public class AutoStart
    {
        //快捷方式名称
        private const string QuickName = "软件名称";

        //系统自启动目录
        private static string SystemStartPath { get { return Environment.GetFolderPath(Environment.SpecialFolder.Startup); } }

        //当前程序的完整路径
        private static string AppAllPath { get { return Process.GetCurrentProcess().MainModule.FileName; } }

        //自动获取桌面 的目录
        private static string DesktopPath { get { return Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory); } }

        /// <summary>
        /// 设置开机自动启动
        /// </summary>
        /// <param name="on"></param>
        public static void setAutoStart(bool on = true)
        {
            //获取启动路径应用程序快捷方式的路径集合
            List<string> shortCutPaths = getQuickFromFolder(SystemStartPath, AppAllPath);
            if (on)
            {
                //开机启动
                if (shortCutPaths.Count >= 2)
                {
                    for (int i = 1; i < shortCutPaths.Count; i++)
                    {
                        deleteFile(shortCutPaths[i]);
                    }
                }
                else if (shortCutPaths.Count < 1)
                {
                    createShortcut(SystemStartPath, QuickName, AppAllPath, "船体协同设计平台");
                }
            }
            else
            {
                //开机不启动
                if (shortCutPaths.Count > 0)
                {
                    for (int i = 0; i < shortCutPaths.Count; i++)
                    {
                        deleteFile(shortCutPaths[i]);
                    }
                }
            }
        }

        /// <summary>
        /// 获取指定文件夹下的快捷方式路径集合
        /// </summary>
        /// <param name="dir"></param>
        /// <param name="targetPath"></param>
        /// <returns></returns>
        private static List<string> getQuickFromFolder(string dir, string targetPath)
        {
            List<string> tmpStrs = new List<string>();
            string[] files = Directory.GetFiles(dir, "*.lnk");
            if (files == null || files.Length < 1)
            {
                return tmpStrs;
            }
            for (int i = 0; i < files.Length; i++)
            {
                if (targetPath == getAppPathFromQuick(files[i]))
                {
                    tmpStrs.Add(files[i]);
                }
            }
            return tmpStrs;
        }

        /// <summary>
        /// 获取快捷方式的目标文件路径，用于判断是否已经开启了自动启动
        /// </summary>
        /// <param name="shortcutPath"></param>
        /// <returns></returns>
        private static string getAppPathFromQuick(string shortcutPath)
        {
            if (System.IO.File.Exists(shortcutPath))
            {
                WshShell shell = new WshShell();
                IWshShortcut shortcut = (IWshShortcut)shell.CreateShortcut(shortcutPath);
                return shortcut.TargetPath;
            }
            else
            {
                return string.Empty;
            }
        }

        /// <summary>
        /// 创建快捷方式
        /// </summary>
        /// <param name="dir"></param>
        /// <param name="shortcutName"></param>
        /// <param name="targetPath"></param>
        /// <param name="description"></param>
        /// <param name="iconLocation"></param>
        /// <returns></returns>
        private static bool createShortcut(string dir, string shortcutName, string targetPath, string description = null, string iconLocation = null)
        {
            try
            {
                if (!Directory.Exists(dir))
                {
                    Directory.CreateDirectory(dir);
                }
                //合成快捷方式路径
                string shortcutPath = Path.Combine(dir, string.Format("{0}.lnk", shortcutName));
                //创建快捷方式对象
                WshShell shell = new WshShell();
                IWshShortcut shortcut = (IWshShortcut)shell.CreateShortcut(shortcutPath);
                shortcut.TargetPath = targetPath;//指定目标路径
                shortcut.WorkingDirectory = Path.GetDirectoryName(targetPath);//设置起始位置
                shortcut.WindowStyle = 1;//设定运行方式为常规
                shortcut.Description = description;//设定备注
                shortcut.IconLocation = string.IsNullOrWhiteSpace(iconLocation) ? targetPath : iconLocation;//设置图标路径
                shortcut.Save();
                return true;
            }
            catch (Exception e)
            {
                MessageBox.Show(e.Message);
                throw;
            }
        }

        /// <summary>
        /// 删除文件
        /// </summary>
        /// <param name="path"></param>
        private static void deleteFile(string path)
        {
            FileAttributes attrs = System.IO.File.GetAttributes(path);
            if (attrs == FileAttributes.Directory)
            {
                Directory.Delete(path, true);
            }
            else
            {
                System.IO.File.Delete(path);
            }
        }
    }
}