The function of retaining wall is to prevent soil landslide and ground collapse and protect the stability of buildings and roads. When building a retaining wall, we usually choose the land occupying the lower side, because the lowlands usually have higher terrain stability and better drainage conditions. Occupation of low-lying land can control soil moisture and drainage more effectively and reduce the risk of soil liquefaction and sliding. Moreover, occupying low land can also reduce the height of retaining wall and reduce the difficulty and cost of the project. Therefore, retaining wall masonry usually chooses to occupy the low side.