Abstract: In order to solve the serious threat to technical reconstruction and the follow-up safety production caused by the previous small mine failure zone and th e spontaneous combustion area existed in the top seam of the contiguous seams in Yuanbaowan Mine,a surface ground radon measuring method was firstly applied to determine the location of the fire area,secondly the sectional simultaneous pressure rising measures was applied to reduce the safety threat of the fire area to the new operation section. A combined nitrogen injection treatment at the surface ground and in the underground mine was conducted in the mining goaf of No. 4 seam to reduc e the fire situation of the fire area. The nitrogen injection in No. 6103 coal mining face was to restrain the residual coal spontaneous combustion in the goaf of the coal mining face. Finally,a grouting sealing was conducted in the goaf. The site observation results showed that the CO content in the goaf was reduced from 5 000 x 10-6to 200 x 10-6,the temperature in the goaf was reduced from 45 °C to 21。C and thus the coal spontaneous combustion danger of No.6103 first coal mining face threatened to the technical reconstruction was effectively controlled.