The current analysis method of pile foundation under horizontal load are analyzed comprehensively. First, mechanics model of rigid pile in slope considering pile lateral stress is established. Second, according to the principle of limit equilibrium, the bending moment and stress equilibrium equation of rigid pile in slope under lateral load are proposed. Then the pile lateral ultimate bearing capacity and horizontal resistance coefficient along the depth increasing linear are developed using p-y curve method. The proposed method is applied in the case study, and the results verified the rationality and feasibility of this method by comparative analysis with the existing finite element calculation methods. Finally, the method is used to perform a series of parametric analyses, such as angle of slope, pile soil contact surface coefficient and horizontal resistance coefficient, and some significant conclusions are drawn. The slope Angle, contact surface coefficient of pile and soil has significant impact on the load displacement curve of rigid pile, and the resistance coefficient of pile side soil impact load displacement curve of is not obvious under the action of the lateral load.