Abstract: The sudden instability and fracture of high key strata can cause dynamic disaster for underlying working face. However, it is difficult to reach high key strata for the current mainstream prediction methods of coal and gas outburst. In order to explore the relationship between the pressure arch and the high key strata near working face, according to the condition of 762 working face in 86 mining area of Haizi Coal Mine, the discrete element model is established for coal seam longwall mining to discuss the evolution law of pressure arch, and some conclusions are compared with the microseismic monitoring data. The results show that the scope of pressure arch expands with working face advancing, when it expands to the high key strata, the new arch will generate, which leads to whole shape changing of pressure arch.