Abstract: To implement an automatic brightness control system for an auto-gating image intensifier with a multi-task fast scheduling and processing function, an automatic brightness control system for an auto-gating image intensifier based on the time slice polling method is designed. Integrated within the auto-gating power source, the system comprises a microcontroller, an anode micro-current sampling module, a high-voltage generation module, microchannel plate high-voltage output module, and cathode high-voltage pulse output module. The system software implements a program design architecture based on the time slice polling method, integrating both the gain temperature compensation function for the image intensifier and the external brightness adjustment function. The actual test demonstrates that the high light level response time of the automatic brightness control system proposed in this study is 4.95 ms, and the stabilization time is 398.18 ms. Furthermore, the system has a good linearity of external brightness adjustment function, and the gain temperature compensation function can ensure that the maximum deviation of gain is less than 0.69%. The reliability and practicality of the system design scheme meet the requirements for the automatic brightness control function of auto-gated image intensifiers, thereby providing a design reference for subsequent research on automatic brightness control systems in auto-gated image intensifier power supplies.