Abstract: Spontaneous combustion of coal poses a significant threat to the safety of mining operations. In order to further reveal the coal oxidation stage heat production characteristics and mechanism based on active group transformation, the evolution of exothermic characteristics and its stage property during the oxidation process of Xinqiao anthracite were studied. In addition, in situ Fourier infrared spectroscopy was used to discuss the reasons leading to the oxidation stage of Xinqiao anthracite from the functional group transformation. The results show that the oxidation and self-heating process of Xinqiao anthracite presents two distinct stages. The heat release in the low temperature stage is less, and the deepening of oxidation degree promotes the accumulation of heat release. When the critical temperature reaches 130 ℃, the heat release rate of oxidation accelerates and the heat release increases obviously. From the initial heat release temperature to the critical temperature, and from the critical temperature to 200 ℃, the heat release heat is 127.42 and 572.36 J/g, respectively. The fundamental reason for the staged heat release process of Xinqiao anthracite lies in the formation and consumption of the active groups −OH and −COOH at different reaction temperatures and the continuous thermochemical transformation process. This leads to a gradual accumulation and release of heat.