Abstract: Spontaneous combustion of coal was affected by many factors. In order to study the mechanism of reaction between coal and oxygen, thermogravimetric (TG) experiments were conducted to test the spontaneous combustion characteristics of lignite, 1/3 coking coal and anthracite under different oxygen volume fractions. The characteristic temperature, mass loss, thermal effect and kinetic parameters of coal sample oxidation process were analyzed. The results show that the response characteristics of different coal ranks on oxygen volume fraction are inconsistent, the higher the degree of coal, the more difficult it is for oxidation to occur, it shows that the characteristic temperature increases, the peak value of exothermic heat decreases, and shifts to the high temperature region; with the increase of oxygen volume fraction, it is easier for coal to react with oxygen, and the heat release of lignite, 1/3 coking coal and anthracite increase to 14 131 J/g, 11 424 J/g and 12 263 J/g respectively; the decomposition and combustion stage of coal under intense heat reaction is analyzed, and it is found that the higher the coal rank is, the higher the apparent activation energy is, the apparent activation energy of each coal sample fluctuates under different oxygen volume fraction.