Abstract: In order to investigate the horizontal bearing characteristics of the pile foundation in a loess area, the distribution law for the internal force and deformation of a pile foundation under horizontal loading at the top of a pile was studied. The finite element software ANSYS was used to establish a semi-structural mode for the pile foundation. Combined with a horizontal loading system, the lateral bearing capacity of the pile foundation was deeply explored, and the parameters of pile length and pile diameter were analyzed. The results show that the pile-soil interface has an obvious interaction mechanics behavior under horizontal loading at pile top. The depth of pile-soil interface separation can reach 4.5 d. The influence of pile diameter on the lateral stiffness and horizontal bearing capacity of a pile foundation is more significant than that of pile length, and the seismic energy dissipation capacity of a pile foundation is limited.