Abstract: For the special case above the working face of Tashan Coal Mine, the numerical simulation software was used to study the distribution of oxygen molar concentration in the goaf under different mining distances and different amounts of nitrogen injection and determine the coal spontaneous combustion danger zone in the goaf. Results show that long-distance extraction of gas makes the coal spontaneous combustion danger zone larger. As the mining distance increases, the spontaneous combustion danger zone gradually widens. When the mining distance is 50 m, the rate of widening the spontaneous combustion zone suddenly becomes larger. The ratio of the width of the spontaneous combustion zone on the inlet side to the length of mining distance is 180% higher than that of the mining distance of 30 m to 50 m, and the return side is 140% higher, causing larger risk of spontaneous combustion of coal; nitrogen injection can greatly reduce the coal spontaneous combustion danger zone in the goaf.