using System;
using System.Collections;
using System.Windows.Forms;
using System.IO;

namespace DYBC
{
        
        public class FileExec
        {

                public FileExec()
                {

                }
                
                private static void CopyDirectory(DirectoryInfo OldDirectory, DirectoryInfo NewDirectory)
                {
                        string NewDirectoryFullName = NewDirectory.FullName + @"\" + OldDirectory.Name;

                        if ( !Directory.Exists(NewDirectoryFullName) )
                                Directory.CreateDirectory(NewDirectoryFullName);
                        
                        FileInfo[] OldFileAry = OldDirectory.GetFiles();
                        foreach (FileInfo aFile in OldFileAry) 
                                File.Copy(aFile.FullName, NewDirectoryFullName +  @"\" +  aFile.Name, true);

                        DirectoryInfo[]        OldDirectoryAry = OldDirectory.GetDirectories();
                        foreach ( DirectoryInfo aOldDirectory in OldDirectoryAry )
                        {
                                DirectoryInfo aNewDirectory = new DirectoryInfo(NewDirectoryFullName);
                                CopyDirectory(aOldDirectory, aNewDirectory);
                        }
                }

                //CopyDirectory
                public static void CopyDirectory(string OldDirectoryStr, string NewDirectoryStr)
                {
                        DirectoryInfo OldDirectory = new DirectoryInfo( OldDirectoryStr );
                        DirectoryInfo NewDirectory = new DirectoryInfo( NewDirectoryStr );        
                        FileExec.CopyDirectory(OldDirectory,NewDirectory);
                }

                //DelDirectory
                public static void DelDirectory(string OldDirectoryStr)
                {
                        DirectoryInfo OldDirectory = new DirectoryInfo( OldDirectoryStr );
                        OldDirectory.Delete(true);
                }

                //CopyDirectory And DelDirectory
                public static void CopyAndDelDirectory(string OldDirectory, string NewDirectory)
                {
                        CopyDirectory( OldDirectory,NewDirectory);
                        DelDirectory(  OldDirectory );
                }
        }
}

------解决方案--------------------

用递归法删除.
DirectoryInfo dir = new DirectoryInfo(path);
           DirectoryInfo[] childADir=dir.GetDirectories();
           FileInfo[] childAFiles = dir.GetFiles();

           if (childAFiles.Length > 0)
           {
               for (int j = 0; j < childAFiles.Length; j++)
               {
                   string newFilePath = path + @"\" + childAFiles[j].Name.ToString();
                   File.Delete(newFilePath);
               }
           }
           if (childADir.Length > 0)
           {
               for (int i = 0; i < childADir.Length; i++)
               {
                   string newPath = path + @"\" + childADir[i].Name.ToString();
                   DelDir(newPath);
               }
           }