A USB printer sharing switch device with automatic switching capabilities is provided for multiple computers to share a USB printer. The sharing switch device transfers USB data between the computers and the printer without changing the data format. The automatic switching function is performed by hardware and firmware of the sharing switch device in cooperation with driver software on the computers. In one implementation, the sharing switch device includes multiple USB device controllers corresponding to the multiple computers, and employs multiple switches and a USB hub so that each computer is connected to its corresponding controller and the computer that is currently connected to the printer can communicate with its controller while printing. The current computer transmits a spooling finished command to its controller when spooling is finished. After receiving the spooling finished command, the sharing switch device automatically switches the printer to another computer.