There are various flammable and explosive hazardous gases in the working environment of mines, among which gas is explosive, seriously threatens the lives of frontline workers. Xishan Zhenchengdi Mine was taken as the object, a set of automatic gas monitoring system was designed, with PLC central control processor, combined with high-sensitivity sensors. The field practice showed that the system can effectively monitor the gas concentration, which provided experience for the coal mining industry to develop new gas concentration monitoring equipment.