The invention discloses a USB combination system and method. The system comprises a function selection switch, a controller, a multifunctional device and a USB interface, wherein the function selection switch is used for selecting a working mode; the controller is connected with the function selection switch and used for detecting a selection signal of the function selection switch, identifying the working mode according to the selection signal to organize an interface protocol, and generating a control instruction or setting configuration information; the multifunctional device is connected with the controller and used for receiving the control instruction from the controller and gating the specified working mode according to the control instruction to enable a specified working module to perform data communication with an external device; and the USB interface is connected with the controller and is connected with the multifunctional device and the external device through the controller. According to the system and method, existing USB devices are combined in a form of the working module, and the specified working module is gated as needed, so that the problem of existing USB device redundancy is solved.