我这里主要用到了文件的复制方法

 string SavesUPLoadPath = ConfigurationManager.AppSettings["AWUploadLocation"] + CompanyName + "/";
                        string copySavesUPLoadPath = ConfigurationManager.AppSettings["AWUploadLocation"] + CompanyName + "/";
                        if (!Directory.Exists(SavesUPLoadPath))//判断上传文件夹是否存在，若不存在，则创建
                        {
                            Directory.CreateDirectory(SavesUPLoadPath);//创建文件夹
                        }

                     
                        SavesUPLoadPath = SavesUPLoadPath + FileUpload1.FileName;
                        FileUpload1.SaveAs(SavesUPLoadPath);
                        string NewSaveUPLoadPath = copySavesUPLoadPath + txtRefNO.Text + "-" + DateTime.Now.Year + "-" + DateTime.Now.Month + "-" + DateTime.Now.Day + "-" + DateTime.Now.Hour + "-" + DateTime.Now.Minute + ".pdf";
                        File.Copy(SavesUPLoadPath, NewSaveUPLoadPath);   ---------把文件赋给新的 //复制文件的作用
                        File.Delete(SavesUPLoadPath); --在删除原来的
                        Response.Write(NewSaveUPLoadPath);
                     
                        labeMess.Text = GetGlobalResourceObject("public", "UpLoadPdfsucceed").ToString();
                        btnSearch.Enabled = false;
                        btnUpLoadFile.Enabled = false;