Aiming at the mining pressure transmission problem during the mining of medium-thick coal seams, the numerical simulation method was used to analyze the collapse deformation and stress distribution law of the 9104 fully mechanized coal mining face in the medium-thick coal seam. The field features were used to measure the pressure characteristics and supporting resistance , the initial step pressure during the first collapse was 46 m, the average value of the periodic pressure was 13.8 m, and the dynamic load coefficient was 1.30 ～ 1.93, the simulation result corresponded to the actual measurement, the support working resistance could meet the requirement of recovery mining.