Abstract: When the upper protective layer 11505 working face is mined, it is necessary to eliminate the gas hidden danger in the unloading pressure belt. The mechanical structure model of thin plate is established. Through setting the boundary conditions of four clamped edges, the “valley-like” flexural properties of underlying strata is obtained, and along the working face, thin face is the most dangerous area; by means of the acoustic emission module of RFPA^2D software, the “funnel-like” pressure relief range during the mining of 11505 working face was obtained, and the correctness of the four-sides fixed thin plate model was verified. On the basis of the above theory, gas extraction roadway is arranged in siltstone adjacent to 21# coal, and stratification optimization is carried out for the arrangement of high borehole, all these obtain the good application in site and eliminate the hidden danger of gas in upper protective layer mining pressure relief zone.