Abstract: The soil arching effect plays an important role in cantilever anti-slide piles. By assuming the reasonable arching axis behind the anti-slide piles, a soil equilibrium equation is established to get the maximum height of the soil arching. Then an differential equation is deduced to calculate the earth pressure on baffle of the cantilever anti-slide piles. The results are compared with those by the formula of local regulations in Chongqing and Coublomb's earth pressure. They are checked using the model tests and good agreement is achieved. The results may provide a basis for the design of baffle of cantilever anti-slide piles in Southwest China.