Abstract: In order to investigate rock burst mechanism in thickness variation of deep unburied coal seam, an island working face in Shandong province is considered as engineering practice background.Through microseismic activities and the observed variable thickness of the coal seam along the open-off cut, the influence of coal seam thickness variation on rock burst is analyzed by numerical simulation.The results show that the increasing thickness of the thinning accentuates the increase in stresses.The phenomenon will be more obvious when mining activity approaches the thickness variation of a coal seam.