Method and system for adding or removing a logical unit of a USB mass storage device

A method and apparatus for adding or removing a logical unit of a mass storage device connected to a host computer through a universal serial bus (USB) interface are provided. The method may comprise: dynamically managing a logical unit table associated with the logical unit; generating a corresponding hot plug and play (PnP) event in the mass storage device; and informing the host computer of the hot PnP event. The mass storage device may comprise: a logical unit managing apparatus; a hot PnP event generating apparatus; and an informing apparatus for informing a host computer of the hot PnP event through a USB.