Abstract: Taking 2^# coal seam of Zaoquan Coal Mine as engineering background, the whole process of natural oxidation of this seam from room temperature to 170 ℃ was simulated by a large-scale coal natural ignition experimental platform, and the critical parameters of coal spontaneous combustion such as minimum floating coal thickness, minimum oxygen demand concentration and maximum air leakage intensity were obtained by analyzing the parameters of coal spontaneous combustion.The results of the experiments showed that the experimental shortest natural ignition period of the coal seam was 36 days, and the thickness limit of floating coal, the minimum required concentration of oxygen and the maximum required strength of air leakage were obtained through calculation and analysis.On the basis of different air leakage intensity, the maximum value of floating coal thickness occurs at 60 ℃,and the minimum floating coal thickness is 0.35 m; the maximum value of minimum oxygen demand concentration occurs at 50 ℃,and the upper limit air leakage intensity is negative at 30～110 ℃.Combined with the actual mining conditions at the site, the critical parameters for preventing spontaneous combustion in the 2^# coal seam are proposed, which provides an important theoretical basis to prevent and control the natural combustion of coal mines.