Abstract: A simplified 3-d model with coal seam dip angle of 6°was constructed with Gambit according to the actual size of the mined-out area of 150405 working face in Duanwang Mine; the caving in the mined-out area was in a nonuniform distribution, the expansion coefficient and porosity distribution of the caved material were established according to the "O-ring" distribution model and by taking the gravity factor into account; based on the oxygen consuming rate obtained by the closed oxygen consumption experiments of coal samples, the setting of the nonuniform oxygen consumption iterms of coal was achieved. Combined with the actual situation of 150405 working face in Duanwang Mine, numerical simulation was conducted by the concrete model, the simulated results were then compared with the measured ones in order to verisfy their reliability. The influence of gas drainage intensity on the coal spontaneous combustion was obtained by simulating the change of gas drainage amount, with the increase of gas drainage intensity, the maximum gas concentration in the mined-out area decreased, and the width of the self-ignition oxidation zone tended to decrease on the side of the belt roadway and increase on the side of the track roadway.