Abstract: Air leakage in goaf is one of the important causes of spontaneous combustion of coal. In order to solve the problem that the 61601 working face of longwanggou Coal Mine has two roadways caving difficulties and causes serious air leakage in goaf, the plastic material technology of bag filling is proposed. The optimum ratio parameters of plastic sealing material are obtained by the ratio experiment of plastic material, which proves that it has good sealing and plasticity. The field application results show that the oxygen concentration in goaf is reduced by 8% at most. The implementation of the technical scheme can effectively prevent and control the spontaneous combustion of coal in goaf, ensure the safe mining of working face, and provide valuable technology and experience for the subsequent mining of working face.