Abstract: In order to clarify the risk range of spontaneous combustion of residual coal in 40101 fully mechanized working face of Gaojialiang Coal Mine, the distribution law of "three zones" of spontaneous combustion was studied by combining field measurement and numerical simulation. The beam tube monitoring system was used to monitor the volume fraction of gas in goaf. The results show that O ₂ volume fraction decreases significantly with the increase of goaf depth, and the fitting relationship between O ₂ volume fraction and goaf depth conforms to the law of logistic function; the volume fraction of CO ₂, CH ₄, C ₂H ₆ shows a significant upward trend with the increase of goaf depth; CO volume fraction first increases and then decreases with the increase of goaf depth. According to the results of field measurement and numerical simulation, the width of oxidation zone on the side of return airway in 40101 fully mechanized working face ranges from 19 m to 131 m deep in goaf, and the width of oxidation zone on the side of haulage gateway ranges from 100 m to 163 m deep in goaf. In the absence of other goaf fire prevention measures, the minimum advancing speed of 40101 fully mechanized working face is 4.08 m/d.