Abstract: In order to study the characteristics of seepage and pore water pressure of an open-pit mine slope in the grassland area of eastern China under the near-natural restoration mode, this paper takes the SEEP/W module in GEO software as the parent item and fits the SLOPE/W module to simulate and analyze the characteristics of slope resistance to hydraulic erosion, the change of seepage path and the redistribution of pore water pressure under the condition of heavy rainfall in the mining area. The results show that after the anti-S-type reconstruction of the original internal dump slope, the resistance to hydraulic erosion of the slope is significantly improved, the slope angle of the upper and lower steps of a single step is reduced, the flow velocity of regional inner diameter flow is reduced, and the degree of rainfall infiltration is increased. Affected by the change of slope surface shape, water seepage occurs at all levels of the slope of the original inner dump slope, and the degree of water loss and soil erosion ishigh. After remolding, the seepage density of 15 m and 20 m bench remolding models increased, and there was no obvious water outflow on the slope of inner waste dump. The pore water pressure at the top of the slope is redistributed, the distribution range of negative pore water pressure is increased, and the area of the transition area is relatively uniform, which effectively alleviates the local ponding phenomenon in the upper rock stratum of the slope caused by the difference of permeability coefficient of different rock strata.