Abstract: In order to study the damage mechanism of overburden rock aquifer after coal mining,utilized the fluid-solid coupling analysis system UDEC-Flow of the damage process with rock,according to the geological conditions of working face of the No.6coal seam in LaoSan-gou coalmine,the damage process of the overburden rock aquifer(the aquifer of glutenite,fine conglomerate and coarse sandstone)was analyzed by numerical simulation method.The simulation results show that the crack keep continuously up growth with the working face advancing,the successively breaking and caving of the immediate roof and basic roof led to the formation of water flowing fracture;simultaneously with the face advancing,the previously generated cracks appeared closed,and near the working face generated new cracks again.Taking the No.6coal seam for instance,the difficulty of protecting aquifer was graded,and proposed the protection technology of overburden rock aquifer,Such as speed up the working face advancing,grouting reinforcement,reducing the mining height,Filling mining and technical of partial mining and so on.Research resluts could provide references for the No.6coal seam and coalmining with the same geological conditions.