Abstract: In the design of retaining wall support for filling in mountainous areas, the width of the foundation of the retaining wall has a greater impact on the amount of work and the difficulty of construction of the foundation excavation project.Through the study of the stability calculation formula of the cantilever-type retaining wall, combined with the retaining wall calculation software,comparative analysis of the minimum foundation width and aspect ratio of ordinary cantilever-type retaining wall and tenon foundation cantilever-type retaining wall under different retaining wall heights.Studies have shown that the use of tenon and anchor rod foundation structural optimization methods can make cantilevertype retaining walls remain stable under a smaller foundation width; as the height of the retaining wall increases, the structural optimization method of tenon and anchor rod foundation has more obvious optimization of the width of the retaining wall foundation, tenon optimization amount is 1.9% ～ 14.7%, tenon + anchor rod foundation optimization amount is 19.4% ～ 38.9%; after structural optimization, the aspect ratio of the cantilever-type retaining wall at different heights does not change much, the tenon is 2.9, and the tenon + anchor rod foundation is 3.5.Tenon + anchor rod foundation cantilever-type retaining wall has more advantages in mountain fill support with good rock and soil properties.