Abstract: The present invention relates to a serially connectable USB drive. The USB drive has an upstream and a downstream port to facilitate the serial connection of other USB drives or the networking of other USB peripheral devices. The USB drive is equipped with a switch circuit. In the case that another serially connectable USB drive or a standard USB drive is inserted into the downstream port, the switch circuit executes the serial connection controlling function and connects the memories of both USB drives. In the case that a standard USB peripheral device is inserted, the switch circuit changes figuration into a USB HUB for the memories of USB drive and the USB peripheral device to communicate respectively with the computer mainframe or other microprocessor units.