In order to study the changes of spontaneous combustion characteristics of bituminous coal with different degrees of metamorphism, according to the order of metamorphism degrees from low to high, four types of bituminous coal with different degrees of metamorphism were selected: Ningxia Lingwu non-stick coal, Ningxia Lingwu gas coal, Shanxi Huozhou 1/3 coking coal and Liaoning Shenyang lean coal, and liquid nitrogen adsorption experiments, Fourier infrared spectroscopy experiments and TG-DSC simultaneous thermal analysis experiments were conducted respectively. The results showed that the specific surface area of internal pores of bituminous coal gradually increased with the increase of the degree of metamorphism, and the pore volume changed in the same trend; the proportion of active functional groups in coal samples gradually decreased, and the proportion of chemically stable functional groups gradually increased; the critical temperature T1
and ignition point temperature T4
of bituminous coal gradually increased with the increase of the degree of metamorphism, and the heat release in the combustion stage of coal samples gradually decreased. In summary, the chemical properties of bituminous coal become more stable with the increase of deterioration, and it is more difficult to spontaneously combust; the influence of active functional groups in coal samples is greater than that of pore structure.