The influence of soil particle size and soil layer thickness on the permeability characteristics of open-pit dump was investigated, so as to provide a theoretical basis for the irrigation water consumption for the land reclamation and ecological restoration of open-pit dump. The surface soil outside the open-pit mine dump was selected as the research object, the particle size and soil thickness as the influencing factors, and the 0.5, 1, and 2 mm particle size and 5, 10, 15, and 20 cm soil layer thickness as experimental schemes. According to the principle of soil column experiment, the permeation law of topsoil under the conditions of different particle sizes and soil layer thicknesses was studied by the constant head method. In addition, the cumulative infiltration rate was simulated by the finite element steady-state seepage numerical method from the permeability rates and permeability coefficients of different experimental groups calculated by the soil column experiment, and compared with the physical results. The simulation results are basically consistent with the physical results. Then the gray system theory was used to study the relative correlation of particle size and soil thickness to permeability characteristics. The research results show that under the condition of the same particle size, the permeation rate decreases with the increase of the thickness; under the condition of the same thickness, the permeation rate increases with the increase of the particle size. The relative degree of correlation of particle size and soil layer thickness with permeability coefficient is 0.894 7 and 0.571 6, respectively, and the relative degree of correlation of particle size with permeability coefficient is greater