Abstract: In order to effectively control and prevent coal spontaneous combustion, to ensure safe mining of coal mines, aiming at the problems of mining spontaneous combustion coal seam in Daxing Coal Mine, complicated geological structure and serious igneous rock intrusion disaster, the idea of nitrogen and carbon dioxide inert coupling gas fire prevention and extinguishing is proposed, and the law of coupled gas migration in goaf is studied by numerical simulation. The results are as follows: when the ratio of nitrogen to carbon dioxide is 3∶1, the inerting effect of goaf is the best; when the injection point of coupling gas is located 45 m away from side goaf of transport roadway, the inert coupling gas injected at this location has the best inerting effect on goaf.