To study the stress and deformation issues of highway bridge pile foundations located on slopes, this paper uses finite element simulation technology and Plaxis2D software to establish a numerical model. The variation laws of horizontal displacement of the pile body and maximum bending moment of the pier body are analyzed, and the effects of pile diameter, elastic modulus of pile concrete, and slope slope on the deformation and stress of the pile body are further explored. The research results are expected to provide reference for the construction of highway bridges in mountainous areas.