Abstract: Improving the anti-erosion ability of open-pit mine dump slope soil is one of the core issues to control soil erosion and slope stability. In this study, the slope erosion characteristics of open-pit mine dump slope under different rainfall conditions were systematically studied by simulated rainfall test, and the erosion characteristics of dump slope before and after PAM improvement were compared and analyzed. Through a series of physical and mechanical tests, the physical and mechanical properties and microstructure of the soil in the dump after PAM reinforcement were systematically studied. The influence mechanism of modified PAM on the hydraulic erosion characteristics of the dump slope was further analyzed, and the ecological reclamation ability of the modified PAM reinforced dump slope was evaluated. The results show that rainfall intensity is the key factor affecting soil erosion characteristics. With the increase of rainfall duration, the length, width and depth of gully increase gradually, and the proportion of erosion area and the depth of rainwater infiltration increase negatively and exponentially. When the rainfall intensity increases, the maximum values of the above parameters increase linearly, and the runoff rate and sediment yield rate increase first and then tend to be stable. With the increase of rainfall intensity, the initial runoff time is linearly shortened and the average rate is linearly increased. Compared with the undisturbed soil slope, under different rainfall intensities, there is no obvious erosion characteristics on the slope surface of the improved soil slope. The permeability characteristics of the improved soil are reduced, and its anti-disintegration ability, shear resistance and freeze-thaw aging resistance are significantly enhanced. Among them, the cohesion of the improved soil increases by 27.04%, and the internal friction angle increases by 17.12%. The stabilizing mechanism of modified PAM in waste dump slopes lies in its superior cohesive capacity, wherein soil particles are aggregated into a robust structure through polymer bridging and enmeshment. This structure significantly enhances the stability of the soil aggregates and constitutes the core mechanism of the modified PAM to exert the anti-erosion effect. The purpose of this study is to lay a scientific foundation for soil erosion control and ecological reclamation of dump slope in open-pit mine area, and put forward a new strategy to improve the soil properties of dump slope by chemical materials.