Abstract: In order to effectively improve utilization of low concentration gas in Daniuchang Coal Mine and improve the economic benefits of gas power stations, based on Siemens S7-1200 PLC control system, an intelligent mixing system of high and low concentration gas was developed, the main function, structure, key technical equipment and process control principle of it were introduced. The intelligent mixing system can automatically adjust the mixing amount of low concentration gas by automatically monitoring and analyzing the change rules of flow, pressure, concentration and other main parameters of low-concentration gas. The application results show that the gas concentration of the intelligent mixing system is uniform and stable, and the gas generator set operates efficiently and reliably, at the same time, the pressure protection device will not cause the gas extraction pump to “suppress” and has no influence on the safe operation of the gas extraction pump station.