Through coal natural temperature programmed oxidation experiments， temperature programmed experiment system， etc. were adopted， comparison and analysis of coal samples into different concentration CO2 under the condition of the change of related parameters， CO2 inhibiting effect to No. 2 Mine of Yangquan Mining high gas No. 15 coal seam coal oxidation spontaneous combustion was studied. The study showed that CO2 inhibiting effect to No. 2 Mine of Yangquan mining high gas No. 15 coal seam was obvious， especially concentration of 20% CO2 inhibiting effect to coal sample in temperature oxidation phase was strong， the injection of CO2 expelled O2 in coal sample， reduced O2 concentration， delayed the appearance of CO、CH4 etc. Natural oxidation product， and its concentration was lower than coal sample without CO2 injection， reduced oxygen consumption rate of coal samples and CO generation rate， inhibited and delayed coal sample natural oxidation and development.