Abstract: In order to better use oxygen index for early warning of goaf spontaneous combustion accidents, numerical method is used to study the dynamic response mechanism of oxygen distribution on spontaneous combustion stage. The calculated results show that oxygen area becomes wedge-shape structure in early stage, and oxygen distribution can shrink back forward with increasing temperature. Then, the oxidation area width divided by oxygen or temperature index appears three stages which presents overlapping in the second stage. Oxidation area position presents different changing trend when air leakage strength is changed. The oxygen distribution dynamic response mechanism with temperature must be grasped in site, the oxygen index should be applied in early spontaneous combustion stage but the temperature index should be applied in latter stage.