Provided are a USB device, a communication system and a method thereof for work mode switching, where the method for work mode switching of the USB device includes: a USB device is inserted into a host, wherein the USB device is configured with single disk device information and at least one type of work mode information; the single disk device information is sent to the host by the USB device, wherein the single disk device information includes installation information as per which the host installs a function management module; and a work mode is selected by the USB device according to a configuration instruction issued by the function management module of the host and configured as a current valid work mode. According to the present disclosure, the USB device, the communication system and the method thereof for work mode switching are capable of accomplishing work mode switching without reconfiguration of firmware programs requiring interruption of power supply, thereby reducing switching time of work modes.