A synchronous detection NC system is introduced based on an open multiracial PMAC controller and Panasonic servo motor where IPC is used as host computer, PMAC as control system center, and Panasonic servo AC system is used as drive. The PID control model of the servo motor is built with Simulink. When Kp equals to 0.55, KI equals to 1. 8, and KD equals to 0. 04, the simulation is carried out and the result meets the requirement of 0. 05 second. By using Honey Bee NC cutting machine to complete synchronous detection and control of the two servo motors, the synchronous operation error is obtained. The result shows that the servo motor synchronous control system, whose absolute average of relation deviation is 2.919%, reaches the requirements of technology and precision of gas cutting NC system.