Abstract: To ensure the stability of the retaining wall in a lead−zinc mine during subsequent filling, a stress model of the retaining wall was developed based on the hydrostatic pressure theory of filling slurry. The characteristics of different types of filling retaining walls were investigated and analyzed. The thickness and average thickness of the retaining wall were calculated under three conditions: compressive strength, shear strength, and impermeability. Based on the average thickness of retaining wall, a reasonable safety design scheme for thickening was proposed. Research findings indicate that the retaining wall pressure is proportional to the square of the initial filling height, while the maximum bending moment is proportional to the cube of the initial filling height. Consequently, the initial filling height should not exceed 1.4 meters at the stage of passing the retaining wall. C20 concrete retaining walls are most suitable for this lead−zinc mine. Given the varying pressure exerted by the filling slurry at different elevation positions within the stope, the thickness of the retaining wall can be tapered from 0.5 meters at the bottom of the stope to 0.25 meters at the top. The primary structure of the retaining wall consists of C20 concrete and double−layer steel mesh with a diameter of 14 mm and a mesh size of 0.3m × 0.3m, supplemented by geosyncline and double−layer anchor rods to enhance the anti−toppling capability of the retaining wall. When calculating the thickness of the retaining wall, the differential pressure of the filling slurry at various positions should be fully considered, ensuring the stability of the retaining wall and reducing construction costs. These research results can serve as a reference for similar mines.