Abstract: In order to evaluate the impacts on the underground water environment of No.1 mine in Wucaiwan mining area，this paper analyzes and evaluates the hydrogeological condition and current situation of water quality of the mine.The results are as follows：according to the distribution characteristics and water-abundance of aquifer groups in the area，the aquifer groups can be divided into five aquifer groups and a relative water-resistance group.The aquifer with significance of water supply is porosity aquifer in quaternary period.The aquifer is mainly supplied by the lateral runoffs in the southeast.The underground water runs off from the southeast to the northwest and drain through the lateral runoffs in the northwest and evaporation.The hydrochemical type of porosity aquifer in quaternary period in the area are mainly SO₄·Cl-Na，Cl·SO₄-Na and Cl-Na.The results are assessed based on underground water quality standard index method and Nemerow index method.The water quality of underground water in the area is poor in general.Many assessment factors in the water exceed standard.The reason of exceeding standard is due to the strong evaporation，pasturing and wildlife activities as well as the impacts of underground water from Karamori mountain in the north of the area.