The purpose of this study was to study the effect of high oxygen concentration on bituminous coal oxidation. The ignition point data under corresponding conditions were obtained by comparing thermogravimetric experiments and large-scale pyrolysis experiments. Oxidized coals with different oxygen concentrations and temperatures were collected by large-scale pyrolysis experiments and extracted with chloroform. The extracted liquid samples were analyzed by GC-MS and Fourier transform infrared spectroscopy. The extracted oxidized coal was characterized by Fourier transforms infrared spectroscopy. The results show that the ignition temperature measured by the large-scale pyrolysis experiment is more than 200 °C lower than that measured by the thermogravimetric experiment at 20% oxygen concentration. The oxidation activity of coal decreases first and then increases with the increase in temperature. The ether bond formed below 150 °C is oxidized and exothermic above 175 °C, which is likely to be the direct cause of coal seam fire.