Abstract: Yuanbaoshan open pit coal mine is covered by the Quaternary aquifer with strong water abundance formed by the alluvial and proluvial deposits of Yingjin river. In order to protect the ecological environment and groundwater resources of the mining area and reduce the drainage water, it is proposed to adopt the water interception curtain dominated by underground diaphragm wall and supplemented by drilling grouting to intercept the Quaternary aquifer with a fully closed curtain from the aspects of geological conditions, construction technology The feasibility of water cut-off curtain is studied from four aspects: water cut-off effect and economic benefit. The results show that the strength of rock is generally below 10MPa, the permeability coefficient of Quaternary aquifer is 123 ~ 637m/d, and the permeability coefficient of curtain base is less than 0.08m/d, which is allowed by geological conditions; The maximum depth of water cut-off curtain is 75m, and the construction technology is mature; The numerical simulation results show that after the formation of water cut-off curtain, the Quaternary make-up water of the pit decreases by 79.8%, and the water cut-off effect is obvious; The investment recovery time of the project is only 5.04 years, and the economic benefit is remarkable. The water cut-off curtain can fundamentally solve the environmental protection risks, potential safety hazards and economic burden caused by large-scale drainage in Yuanbaoshan open pit coal mine.