DirectoryInfo dir = new DirectoryInfo(@"C:\yourfolder");
FileInfo[] files = dir.GetFiles();
//User Enumerable.OrderBy to sort the files array and get a new array of sorted files
FileInfo[] sortedFiles = files.OrderBy(r => r.Name).ToArray();

对于只有数字(int)名称的文件号,请尝试：

FileInfo[] sortedFiles = files
                          .OrderBy(r => int.Parse(Path.GetFileNameWithoutExtension(r.Name)))
                          .ToArray();