Abstract: Taking the first mining face of 5-20101 working face in Qinglongsi Coal Mine as the background, the theoretical research, numerical simulation and field measurement are used to study the distribution of “three zones” of the mined-out area, the results show that: after the working face mining, according to the distribution of pressure in the goaf, the collapse zone of goaf is divided into natural accumulation zone, accumulation and crushing zone and compaction zone, and there is a basic correspondence between these three zones and the “three zones” of spontaneous combustion in goaf; the concentration of oxygen on the return air side of working face fluctuates greatly, but overall is on the decline, and a large number of mining-induced fractures occur mainly due to the influence of mining on the working face. These cracks are connected with the surface, which causes air leakage in the goaf of the working face. Under the influence of the surface atmospheric pressure, the oxygen concentration changes in the goaf.