Abstract: When the gas and spontaneous combustion hazards exist at the same time in goaf, it is easy to cause gas explosion accidents due to coal spontaneous combustion. Based on the physicochemical properties of CO₂ and N₂, this paper mainly considers the difference in density and the characteristics of adsorption and desorption, and proposes a technique of high level borehole injection of CO₂ and low level borehole injection of N₂ to form the residual coal wrapper layer in the goaf. The technical points are that after the gas drainage from the high level borehole, the borehole is used as gas injection drilling and CO₂ is injected into the goaf from the drilling by pressure and adsorbed by the residual coal; the N₂ is injected into the low level of the goaf from the buried pipe in the upper corner. In order to increase N₂ diffusion effect, pipe is buried in air return corner for gas drainage. After the application of this technology in Tangkou Coal Mine 6307 working face, the problem of gas and fire control in coal mine is solved well.