Abstract: The thick coal seam mining process is affected by the original layering mining technology, and the original goaf is exposed, and the air flow in the working face leaks into the goaf under the action of pressure difference, which is easy to cause the spontaneous combustion of broken residual coal in the goaf and produce a large number of harmful gases. Based on coal pillar （ｎｏｒｔｈ） fully mechanized caving face of main lane of Shuiliandong Coal Mine as an example, based on the analysis of thick coal seam fully mechanized working face and goaf under the condition of the coupling relationship between the flow fields, on the basis of using SF₆ gas leakage test and numerical analysis method, the combination of the working face through the characteristics of the mined-out area in the process of extraction and the law of air leakage, the prevention and control method of coal spontaneous combustion in thick coal seam through goaf based on inert equilibrium is proposed. The results show that there are obvious air leakage channels between the goafs in the coal seam within the range of 200 m from the working face to the cutting hole. The cutting hole of the working face is connected, and the leakage air flow O₂ migrates to the return air side, and its mass fraction decreases with the increase of the distance from the cutting hole. About 100 m out of the cut hole is the danger area of spontaneous combustion in the goaf of the coal seam. Closed-type nitrogen inerting and multi-hole continuous gel injection are adopted to realize the inerting balance of mined-out area, and effectively prevent the spontaneous combustion of mined-out area coal in working face cutting holes, passing through goaf and stoping period.