Abstract: For a high gas coal mine caving in goaf coal spontaneous combustion, with N2202 working face as the engineering background, through field investigation, laboratory test, numerical simulation and industrial experiments and other means of goaf gas injection CO2 prevention of goaf spontaneous combustion ignition and improve the efficiency of gas extraction study. The research shows that different particle size of coal sample showed the adsorption of CO2 gas is higher than that of CH4 gas, and the particle size of coal sample under the condition of mixed CO2 gas injection can effectively exchange adsorption of CH4 gas; Fluent numerical simulation indicates that the mined out area on the CO2 gas injection makes the CH4 gas concentration gradient distribution in gob deep mobile, and can effectively dilute the gob gas accumulation with gas concentration; CO2 gas injection makes the goaf oxidation zone decreases, while resulting in part of the CH4 gas adsorption on coal is replaced, the gas drainage concentration from the original average concentration increased to 49.25% in 35.61%. The empty time zone of spontaneous combustion can effectively improve the level of branch wells of goaf gas drainage efficiency control. The research results provide some reference for the coal mine with high gas and spontaneous combustion.