The photomultiplier tube (PMT) is an important device for micro-light detection, and the detection of light intensity using photon counting method can significantly reduce the interference of noise, but the sensitivity, gain, and dark noise of PMT cathode are easily affected by the ambient temperature, which leads to the instability of the output pulse amplitude and affects the detection performance of the system for micro-light. A high voltage gain compensation and threshold correction system was designed for PMT through microcontroller unit (MCU), digital to analog converter (DAC), and other modules. A hybrid function model of temperature and high voltage compensation increment