Abstract: According to the mining technical conditions of No.8252 down coal mining face in Dongxingtai Mine, the paper analyzed the cause of the spontaneous co mbustion in the coal mining face and the air leakage in the goaf caused the oxidation of the ground coal.A pressure balanced ventilation plan of the diagonal air flow to control the coal spontaneous combustion was provided.With the adjustment of the pressure difference in the diagonal air flow, the pressure balanced status could be re ached to restrain the CO emission. Thus the total CO emission value of No.8252 down coal mining face would steadily be reduced from 0.052 3 m3/min to 0.001 5 m3/m in and the spontaneous combustion danger of the coal mining face was eliminated.