In order to explore the exothermic hazard of coal gangue in the process of spontaneous combustion and its correlation with microscopic groups, the microstructure and exothermic characteristics of four kinds of coal gangue(CG1、CG2、CG3、CG4) were tested by infrared spectrum experiment and differential scanning calorimetry experiment; based on the exothermic heat and activation energy, the spontaneous combustion risk coefficient of coal gangue is established, and the correlation between spontaneous combustion risk coefficient and the microscopic groups is determined. The results show that the four kinds of coal gangue all contain substituted benzene, ‒C=C‒, Ar‒CH, ‒CH3
‒, Al‒CH, ‒OH, ‒C‒O‒, ‒C=O and inorganic compound groups, but the content of each group is significantly different. The exothermic process of self‒ignition of coal gangue can be divided into three stages: water evaporation, slow exotherm and combustion, but the duration of the three stages is different for different coal gangue. The activation energy of the four kinds of coal gangue in the endothermic stage is CG1>CG3>CG2>CG4, while that of the coal gangue in the exothermic stage is CG3>CG4>CG2>CG1. The spontaneous combustion risk coefficients of the four kinds of coal gangue are in the order of CG1>CG2>CG4>CG3, and the correlation between microscopic groups and benzene is in the order of ‒C‒O‒ > substituted benzene > ‒OH> ‒CH3
> ‒C=C‒> inorganic matter > ‒CH2
‒ >Ar‒CH> ‒C=O>Al‒CH> ‒COO‒, the correlation of the first three is greater than 0.85. Therefore, coal gangue with higher levels of ‒C‒O‒, substituted benzene and‒OH has a greater risk of spontaneous combustion.