A method for a communication mode, comprises: detecting the type of the communication mode; if the communication mode is a USB interface communication mode, turning off a timer; when an instruction is received, conducting a corresponding operation according to the USB interface communication protocol supported by the device; if the communication mode is not set, then when the timeout identifier is set, setting the communication mode as a serial port communication mode, turning off the timer, resetting the timeout identifier, and executing step S6; if the communication mode is a serial port communication mode, turning off the timer, and executing step S6; step S6: when the instruction is received, conducting a corresponding operation according to the serial port protocol.