Abstract: High gas flammable coal seams are explored in No.9 mine in Pingdingshan Tian’an Coal Industry Company. In order to prevent the severe oxidation of floating coal on the intake air side in the goaf area of Ⅵ_16.17 -22042 working face, the mine adopts the fire prevention technology of injecting 2 500 m³/h of large flow carbon dioxide, and a total of 105 000 m³ of carbon dioxide is injected into the goaf. The coal mine has studied the gasification method of high-flow carbon dioxide, the process of injecting carbon dioxide into the goaf, the flow direction of carbon dioxide in the goaf, the effect of reducing oxygen and cooling. The results show that high flow of carbon dioxide can effectively inhibit the violent oxidation of floating coal in the intake air side in the goaf, and the CO gas overrun in the goaf is eliminated in only 4 days.