The work aims to design a high-precision servo control system of Z-axis height adjustment for laser cutting based on an STM32 master controller chip and an FPGA slave controller chip. The principle, hardware design, software design and simulation experiment of micro capacitance measuring circuit of the control system were introduced. Aiming at the interference of servo control system, an improved filtering operator based on moving average filtering algorithm was put forward. Laser cutting test was conducted to verify the proposed method. The dynamic following accuracy of the servo control system was 0.01 mm, and the maximum following speed was 500 mm/s. The servo control system enables laser cutting machines to achieve high speed and high precision cutting effect.