Abstract: The method of pumping and discharging groundwater is widely used in open-pit coal mines for groundwater control in China to meet the requirements of safe coal mining, which causes great damage to water resources and seriously affects the ecological environment around coal mines. In recent years, with the all-round development of the economy, China has put forward higher requirements for ecological environment protection and ecological civilization construction. How to optimize and change the groundwater control mode and reduce the volume of pit drainage is a new subject generally in water prevention and control of open-pit coal mines. The use of the water cutoff curtain technology instead of drainage and dewatering technology is the fundamental measure to solve many problems caused by drainage in open-pit coal mines. Taking the implementation of the water cutoff curtain technology in Zhanihe open-pit coal mine and Yuanbaoshan open-pit coal mine as an example, this paper introduces the design concept, construction process and materials of the water cutoff curtain technology for open-pit coal mines in China. In the practice, the technical bottleneck of large-depth vertical concealed laying and complete connection of impervious membranes is broken through, and the continuous excavation and pouring technology of super long grooves is developed, greatly reducing the number of joints. The composite curtain material of fly ash-cement mixed slurry and HDPE geomembranes is developed to improve the impermeability and deformation resistance of the curtain. The comprehensive inspection system for curtain quality and water interception effect is constructed, and the key technologies of curtain construction are mastered. The successful application of water cutoff curtain technology in China enriches the technical theory of water control and water resource protection in open-pit coal mines, promotes the technical progress of the industry, and provides new ideas, new technologies and new processes for groundwater control and safe and green mining in open-pit coal mines. It has important reference significance for other non-coal mines, water conservancy, hydropower, transportation and other projects with higher anti-seepage grade requirements.