The traditional method of adjusting the gain of photomultiplier tube (PMT) with mechanical knobs not only has disadvantages of manual operation based on experience and poor accuracy, but also has a disadvantage that the gain of PMT is susceptible to temperature and the high voltage of PMT needs to be dynamically adjusted according to the ambient temperature. These limitations are not conducive to its application in lidar system. In order to adjust thegain of PMT easily and keep the stability of PMT gain, the control circuit board of PMT applicable to lidar system is designed to realize gain regulation and high-voltage temperature self-adaptive adjustment by computer, thus simplifying the structure and volume of the signal detection system and improving the stability of the signal. In this work, H10721-20 type PMT with built-in high voltage power supply is used, and the corresponding control circuit board based on STM32 single chip microcomputer, digital-to-analogue converter and peripheral circuit is designed and manufactured. Further, the high voltage stability of PMT controlled by potentiometer is compared with that of PMT adjusted by the control method proposed in this work, and then the performance of Mie scattering lidar using the designed PMT control circuit board is tested. The experimental results show that the control method proposed in this work can achieve more stable PMT gain control, which indicates that the designed PMT control circuitboard has good reliability.