An optical disc drive and a method of reading an optical disc are disclosed. The drive includes an I/O port, an optical pickup module and a format conversion unit. The I/O port couples a host to receive a read command of a host terminal file system format. The optical pickup module accesses the optical disc which contains data of a first file system format. The format conversion unit coupled between the I/O port and the optical pickup module includes a mapping information generation module, a memory module and a read-command processing module. The mapping information generation module controls the optical pickup module to access data and thereby to generate mapping information. The memory module stores the mapping information. The read-command processing module controls the optical pickup module to access the optical disc according to the read command by referring to the mapping information.