Abstract: The development of the lower coal seams(No.16 and No.17 coal seams) which own abundant reserves and good existing geological conditions in the south of Liangbaosi Area is threatened by the karst water of Ordovician-the basement of the C-P coal bearing strata.On the basis of studying the karst feature of Ordovician limestone,the characteristic of Ordovician karstwater is analyzed as well as the possibility of the water filling of mine and its affecting factors are presented in this paper.