Abstract: In the process of open-pit coal mining, drainage is an important aspect causing the loss of groundwater resources. Taking Yuanbaoshan open-pit coal mine in Chifeng City, Inner Mongolia as the research object, this paper analyzes the control principle of the curtain wall construction driven by open-pit mining on the groundwater system according to the hydrogeology of the study area and the characteristics of open-pit coal mine development. It comes to the conclusion that the weaker the permeability of the curtain wall, the greater the thickness, and shortening the distance from the recharge water body is the basic idea of reducing water inflow in open-pit mining. The numerical simulation research of open-pit mining drainage and groundwater system are combined to predict and analyze the influence of open-pit coal mining and curtain wall construction on the drainage intensity of the pit. The simulation results show that for the local curtain scheme of the main water inflow section, the open-pit pit is still taken as the center of the falling funnel, and the regional flow field has not changed significantly. In the section without a curtain, a strong lateral flow phenomenon occurs in the groundwater. The residual water inflow of the mine in the initial stage (300 d) reduces at most 37.16% compared with the drainage of the current mine, and the residual water inflow increases obviously with time. After the construction of the wall in the quasi fully closed curtain scheme, the roundabout flow phenomenon hardly occurs in the groundwater. The residual water inflow of the mine tends to decrease first and then increase with the maximum reduction of 85.79%, and the increase of water inflow in the later stage is not significant. It can be seen that the quasi closed curtain construction scheme has a significant effect on reducing the overall water inflow of the mine compared with the local curtain scheme. By analyzing the water control law of lateral curtain in open-pit coal mining, a simulation model of the groundwater system under the condition of water blocked by the curtain is constructed, and the effect of discharge reduction by the water interception curtain is evaluated, providing a scientific basis for the coordinated development of coal-water resources in open-pit mining areas.