Abstract: To prevent rockfall water disasters and surface subsidence geological hazards caused by underground mining in the east wing of the Xinqiao Sulfur-Iron Mine during the process of open-pit to un⁃ derground mining, a vertical sealing curtain grouting project is implemented on the outer side of the east wing open-pit slope. This provided guarantees for the subsequent safe underground mining in the east wing. Based on the results of ground karst hydrogeological investigation, the distribution characteristics of karst development in the underground of the mining area were revealed. The grouting effect of the curtain is comprehensively evaluated from multiple aspects such as the grouting volume of each sequence of bore⁃ holes, water pressure tests, and changes in groundwater levels of observation holes outside the curtain. The results showed that the groundwater levels of the observation holes outside the curtain generally rose, the water-blocking effect was obvious, the water inflow in the curtain decreased significantly, indicating that the curtain effectively blocked the karst channels, and the water-blocking effect was remarkable. After the curtain was completed, it not only effectively ensured the safety of mining in the mine, saved a huge amount of drainage costs, but also prevented the occurrence of karst subsidence geological disasters in the mining area. The research results can provide technical references for the evaluation of water prevention and con⁃ trol curtain engineering effects in similar mines.