Abstract: Coal gangue is produced in the washing and processing process of coal mining. Without treatment, it is dumped naturally to form a gangue mountain. Long-term heat storage leads to spontaneous combustion. Affected by coal quality of coal seam, there are many kinds of coal gangue, among which the washing gangue with high sulfur content has a large tendency of spontaneous combustion in concentrated discharge. The gangue hill of Checkerjing Town in Inner Mongolia is mostly washing gangue accumulation, and part of it has been spontaneous combustion for a long time, which seriously threatens the environment and residents’ health. In order to forewarn spontaneous combustion of gangue and treat burned gangue scientifically and efficiently, it is necessary to study the whole process of spontaneous combustion of medium-high sulfur gangue in this area and analyze the law of gas precipitation at each stage of spontaneous combustion. In this paper, synchronous thermal analysis and mass spectrometer system (TG-MS) were used to obtain the synchronous changes of mass, heat and gas precipitation in the oxidation and combustion process of medium-high sulfur coal gangue, and the correlation analysis was conducted by Spearman correlation coefficient method according to the data characteristics. The results show that the existence of pyrite in medium-high sulfur gangue can promote spontaneous combustion. According to the characteristic temperature point oxidation combustion process can be divided into five stages: I pyrite oxidation and gas desorption stage, II oxygen absorption weight gain stage, III volatilization analysis stage, IV combustion stage and V burnout stage. At each stage, H₂S, CH₄, CO and NO gases were precipitated, showing an increasing trend, while SO₂, CO₂ and NO₂ gases were precipitated in large quantities at the III and IV stages. Spearman correlation analysis showed that there was a high negative correlation between the amount of gas precipitated and the change of mass, and R_SO2=R_CO2=R_NO2>R_CO>R_NO>R_H2S>R_CH4. In addition, the mass precipitation of SO₂, CO₂ and NO₂ gases at stage III and IV is highly negatively correlated with mass reduction (correlation coefficient is -1).In the future, we can continue to study the monitoring, sensitivity and selectivity of SO₂, CO₂ and NO₂ gases, analyze their feasibility as indicator gases, and provide a new idea for spontaneous combustion early warning of gangue hills.