Abstract: In this paper, the authors have analyzed the hydrochemical characteristics in karst water of the coal seam floor in the mining area of North Anhui and studies the circulation characteristics of the Karst water by means of the concentration grads of water quality and hydrochemical equation of Ca²⁺. It is pointed out that TDS and △Ca²⁺ in the Karst system of the mining district have a increasing trend from north to south and there is a low value zone of TDS and △Ca²⁺ in the north and two high value zones in the south.