Abstract: In order to research evolution law of the below coal and seam stress effect and estimate the effect of protective layer mining on Qinglong Coal Mine, the maximum principal stress distribution was studied by numerical simulation, and the deformation characters and gas flow of the protected layer were inspected on the spot, the pressure relief laws of protected layer during protective layer mining was analyzed. The results show that the maximum principal stress in advancing direction are in the terms of four-zone, the maximum release rate of stress is 43% in pressure relief zone, the relative expanding deformation rate increase to 4.9‰, gas flow increase to 0.194 m³/min with 28 folds, the regularity of deformation and gas flow correspond with the result of numerical simulation.The effect of gas extraction would be improved by perforating reasonable perforating arrangement because gas emission is easier in the pressure-relief zone.