A computer numerical control (CNC) machine includes a case, a communication plug, a first switch, a number of second switches, and a control circuit. The control circuit includes a first switch control unit to receive a first switch signal from the first switch, a second switch control unit to receive second switch signals from the second switches, a control unit, a command signal converting unit, a pulse signal generating unit, and an operation signal output unit. The control unit receives the first and second switch signals, determines the work mode of the CNC machine according to the first switch signal, and convert the second switch signals to command signals. The command signal converting unit converts the command signals into operation signals. The pulse signal generating unit generates pulse signals. The operation signal output unit outputs the operation signals and the pulse signals to the CNC machine via the communication plug.