In order to improve the quality and reliability of laser cutting system, because of the undulating surface of workpiece, a laser cutting head servo system based on STM32 and PCAP01 was designed. It used PCAP01 to get the capacitance between the nozzle on laser cutting head and the surface of workpiece. The distance was calculated by capacitance, after Kalman filtering,which was used to keep the distance between laser cutting head and workpiece. The results show the equipment has good quality and reliability...