Abstract: In recent years, the SF₆ gas leakage problem of the gas insulated switcher (GIS) equipment due to the product quality, installation process and complex operating environment has gradually become prominent as the equipment of GIS has become the mainstream equipment in 110 kV and above substations. But the SF₆ gas leakage defects often cannot be dealt with in time because they involve problems such as power outage plan, construction period and process difficulty. This paper presents an automatic pressure maintaining system for gas leakage chamber of GIS, which has the following characteristics: It can realize automatic control for SF₆ gas replenishment, so that the SF₆ gas leakage chamber can be replenished in time when the pressure drops to the alarm value. It can achieve multi-mode operation including the manual remote, automatic control and local control. The double safety structure combined with the solenoid valve and check valve can effectively forestall the gas back-flow. The SF₆ cylinder group is connected in parallel to provide sufficient gas pressure, and the system can dynamically monitor the gas pressure state of the cylinder group, and has the function of low-pressure remote alarm to remind the maintenance personnel to replace the cylinder in time. The system can count the gas leakage rate through the counting function and upload it to the cloud, providing a reliable basis for the maintenance personnel to count the air replenishment cycle and disassembly maintenance. In this paper, the feasibility of the device is verified by making a physical simulation system of automatic pressure maintaining.