Abstract: This article had carried on thermo gravimetry experiments on coal samples from Shuozhou Xingtao Coal Mine and Changzhi Changcun Coal Mine, and obtained the characteristic temperature points at the oxygen concentration of 5%, 10%, 15%, 17%, 21% and 30% when the heating rate was 10 K/min, respectively. The coal ignition decreased as oxygen concentration increased. Coats-Redfen integral formula is used to calculate the activation energy of the zone which was from ignition temperature to combustion end temperature. It revealed the activation energy increased with oxygen concentration increasing. And the activation energy of Xingtao Coal Mine was less than the one of Changcun Coal Mine, and spontaneous combustion of Xingtao Coal Mine occurred more easily. For the same coal sample, TG curve drifted to the left with the increase of oxygen concentration. It indicated that the increase of the oxygen concentration shorted the reaction time within a certain range, the coal sample was more likely to be burning.