The bearing capacity of the foundation can be significantly increased by using a pile joist retaining wall structure, which also has strong practical value for treating soft soil foundations and preventing slopes. The classic continuous beam model, which is relatively ideal and prone to mistakes, is utilized in the current theoretical calculation to solve the stress characteristics of joist or piling foundation. In this paper, based on the static balance condition of the earth pressure behind the retaining wall, the earth pressure load behind the wall is solved and used as the input load of the joist and pile foundation. Then, based on the finite difference principle, the supporting beam is regarded as the beam theory on the Winkler foundation, and the finite difference method of the internal force of the supporting beam is proposed. Further considering the characteristics of the foundation coefficient of the pile foundation changing with depth, that is, the ' m ' method, the finite difference method is used to solve the stress characteristics of the pile foundation. Then the solution method in this paper is compared with the traditional calculation method. the results show that the traditional model of continuous beam theory ignores the soil resistance, it’s too small to evaluate the bearing capacity of the structure, the elastic foundation beam solution method in this paper can better reflect the actual engineering situation, and its calculation results are more reliable. If the double-row piles bear different loads according to a certain proportion, the displacement, bending moment and shear force of the rear-row piles will increase with the increase of the load. The research results can provide a theoretical basis for engineering slope protection.