Abstract: A MP3 player and a method for operating the same are proposed. The MP3 player includes a command input device, a bus switch device, and a player control device, and is installed in a computer having a central processing unit (CPU), a hard disk, and a sound output device. In operation, upon receiving a command inputted by the command input device, the bus switch device is urged to connect the hard disk to the player control device, allowing the player control device to read and execute MP3 files stored in the hard disk. As the MP3 player directly reads MP3 files from the hard disk, songs stored in the MP3 files can be more efficiently played. And, the hard disk provides large capacity for storing MP3 files, thereby saving costs for an expensive flash memory used in the prior art.