我不知道哪种解决方案更好，但我用这个:

String[] ext = "*.ext1|*.ext2".Split('|');

            List<String> files = new List<String>();
            foreach (String tmp in ext)
            {
                files.AddRange(Directory.GetFiles(dir, tmp, SearchOption.AllDirectories));
            }

/// <summary>
/// Returns the names of files in a specified directories that match the specified patterns using LINQ
/// </summary>
/// <param name="srcDirs">The directories to seach</param>
/// <param name="searchPatterns">the list of search patterns</param>
/// <param name="searchOption"></param>
/// <returns>The list of files that match the specified pattern</returns>
public static string[] GetFilesUsingLINQ(string[] srcDirs,
     string[] searchPatterns,
     SearchOption searchOption = SearchOption.AllDirectories)
{
    var r = from dir in srcDirs
            from searchPattern in searchPatterns
            from f in Directory.GetFiles(dir, searchPattern, searchOption)
            select f;

    return r.ToArray();
}

是什么

string[] filesPNG = Directory.GetFiles(path, "*.png");
string[] filesJPG = Directory.GetFiles(path, "*.jpg");
string[] filesJPEG = Directory.GetFiles(path, "*.jpeg");

int totalArraySizeAll = filesPNG.Length + filesJPG.Length + filesJPEG.Length;
List<string> filesAll = new List<string>(totalArraySizeAll);
filesAll.AddRange(filesPNG);
filesAll.AddRange(filesJPG);
filesAll.AddRange(filesJPEG);

对于。net 4.0及更高版本，

var files = Directory.EnumerateFiles("C:\\path", "*.*", SearchOption.AllDirectories)
            .Where(s => s.EndsWith(".mp3") || s.EndsWith(".jpg"));

对于。net的早期版本，

var files = Directory.GetFiles("C:\\path", "*.*", SearchOption.AllDirectories)
            .Where(s => s.EndsWith(".mp3") || s.EndsWith(".jpg"));

编辑:请阅读评论。Paul Farry提出的改进，以及Christian提出的记忆/性能问题。K点都很重要。

Nop……我相信你必须拨打尽可能多的你想要的文件类型。

我会自己创建一个函数，在我需要的扩展字符串上使用数组，然后迭代该数组，进行所有必要的调用。该函数将返回与我发送的扩展名匹配的文件的通用列表。

希望能有所帮助。

没有。试试下面的方法:

List<string> _searchPatternList = new List<string>();
    ...
    List<string> fileList = new List<string>();
    foreach ( string ext in _searchPatternList )
    {
        foreach ( string subFile in Directory.GetFiles( folderName, ext  )
        {
            fileList.Add( subFile );
        }
    }

    // Sort alpabetically
    fileList.Sort();

    // Add files to the file browser control    
    foreach ( string fileName in fileList )
    {
        ...;
    }

摘自:http://blogs.msdn.com/markda/archive/2006/04/20/580075.aspx