The coal bearing stratum of Yuanbaoshan open-pit coal mine is covered by the Quaternary gravel layer with strong water yield formed by the alluvial and proluvial deposits of Yingjin River. Since the mining of the mine pit, the drainage water is beening huge, he quaternary system water inflow accounts for 95% of the total drainage, resulting the environmental risk and economic burden have been increasing. In order to effectively protect the groundwater resources and reduce the drainage volume of the mine, adopted the curtain water cutoff curtain technology of vertical concealed laying of impermeable membrane and pouring and filling of impermeable concrete to treatment the quaternary groundwater. A falling bottom water interception curtain with a plane length of nearly 3600m, effective thickness of more than 0.8m, and wall depth of more than 40m was built on the +452 m flat plate at the southeast side of the mine pit. Verified by physical excavation, comparison of water levels on both sides of the curtain and change of water volume in the pit, the water cutoff curtain effect is remarkable, which completely solves the problem of quaternary groundwater infiltration in the southeast of the pit. The implementation of the water cut-off curtain in Yuanbaoshan open pit coal mine once again verified the feasibility of the curtain water cut-off technology in the seepage interception and emission reduction of open pit coal mines, which has important demonstration and promotion significance for open pit coal mines and other mines with similar problems.