A numerical analysis method was presented to study the behavior of the laterally loaded pile considering the characteristic of the contact interface. The test data of piles under lateral loaded piles were used to analyze the effect of contact interface on laterally loaded piles. FEM was used to compare the results of the horizontal loaded single pile using different interfaces. The displacement curves of the pile computed show that as to horizontal loaded piles, there is a critical value of the depth of pile in soil, and the excess depth is useless.