Abstract: The paper introduces not only the hardware construction and software function of the RF-500 coating machine but also hardware composition and software architecture the new computer control system. A PC-based control system is developed for RF-500 chemical vapour deposit （CVD）coating machine in order to overcome shortcoming of traditional control manner. Lots of experiments are perform about substrate temperature, gas flow and swiching value aiming to obtain satisfactory control effect.The research resoults indicate that temperature control error ±1 ℃ is obtained and flow control error is 10 mL /min. The application indicates that the control system can real-time monitor performance of RF-500 CVD coating machine