Understanding the pile behavior and predicting the capacity of piles under horizontal load are important topics in foundation design. In this paper, the mechanical characteristics of single pile under horizontal load is analyzed based on FLAC3D finite difference software, and the load-displacement curve, the bending moment, shear force, soil resistance under all levels of load and the distribution law of p-y curve along the pile shaft are obtained. accordingly the following conclusions can be made: the bending moment of the upper part of pile body is big, the maximum bending moment is at the height of 2~3 meters and it is almost zero below the depth of 9 meters. The bending moment increases with the increase of load, the point of maximum bending moment moves down along the pile body with the increasing of horizontal load. and the location of the point of maximum bending moment moves from 2 meters below the ground to 3 meters below it. The distribution of soil resistance along the pile shaft is a reverse "S", the maximum of pile lateral soil resistance is at the height of about 2~3 meters below the ground.
