Abstract: A new model is established to describe the relationship between permeability and stress according to the distribution characteristics of overlying rock permeability with the stress change under mining-induced condition. The permeability-stress model, through the fish language, is embedded into the FLAC^3D software to simulate the change law between permeability and stress of the overlying strata. At the same time, the permeability change is used to determine the height of the pressure relief zone. Numerical results show that the permeability decreases with the increase of stress; the pressure releasing height increases with the increase of the mining distance, but the final value tends to a constant value; the protective layer can enhance the permeability of the coal layer, and can effectively improve the efficiency of gas drainage; after being protected by the protective layer, the permeability of the overlying strata in the mined area is about 3 times that of the overlying strata.