Abstract: A system and method of downloading and playing the downloaded music files comprises a music website that provides, through a network, music files with searchable indexing page, and a plurality of information terminals that are capable of communicating with the music website through the network and downloading and playing the music files downloaded from the music website. If it is a karaoke song, the music file is marked with position indictor at each point of changing word of lyrics along with melody of the song for synchronization. The music files will be removed from the memory of information terminal after online playing. For offline playing, the music files are encrypted when being downloaded, and will be decrypted at the information terminal for playing with verification of correct encryption key stored in the information terminal. The encryption key is created and updated regularly with the update of the virtual amplifier so as to prevent the user from distributing freely the downloaded music files.