Abstract: The FLAC^3D numerical simulation software is used to analyze the strata movement rule under different mining height so as to provide some theoritical foundations for the mining safety of the Shendong mining area and it's ground protection. The research results show that,the overlying strata subsidence tends to increase along with the increase of the mining height and it tends to decrease along with the increase of the distance from the overlying strata to the coal seam under the same mining conditions.According to the simulation results, the movement of overlying strata that close to the coal seams increases sharply and the cut down type sinking of overlying strata occurs, it maybe caused by the breaking of key layers.The type of slowly sink occurs in the overlying strata that far form the coal seam, it is because that the overlying strata plays a supporting role.

Key words: Mining height, Strata movement, Numerical simulation, Mining subsidence