Abstract: Aiming at the prevention problem of spontaneous combustion during the mining of close coal seam groups in Xinwei Coal Mine, taking 3102 working face of the first mining of 3^# coal seam as an example, the research on the grading early warning technology of spontaneous combustion in the goaf was carried out through the combination of indoor experiment and field practice. The results of the coal oxidation temperature programming show that the spontaneous combustion and oxidation of the 3^# coal seam is inhibited under the condition of 10% oxygen concentration; the inhibitory effect is more obvious under the condition of 7% oxygen concentration; the natural coal oxidation process presents obvious phase CO gas production characteristics. Based on this, the spontaneous combustion warning in the goaf is divided into four warning levels, corresponding to the slow oxidation （24×10^-6-200×10^-6）, accelerated oxidation （200×10^-6-500×10^-6）, violent oxidation （500×10^-6-4 000×10^-6） and combustion （>4 000×10^-6） in four stages. In line with the basic principles of economic disaster control, the spontaneous fire prevention plan is dynamically adjusted according to different warning levels, and the hidden danger of spontaneous combustion in the mining process of the working face has been successfully dealt with to ensure the safe mining of the mine.