Abstract: Conventional methods of researching the behaviour of laterally loaded piles are usually based on the assumptions of the relations between the horizontal displacement of the pile and the reactive force of soil along the depth. By analyzing the observed data from field tests, an equation is proposed in this paper, with which the bending moment distribution along a laterally loaded pile is simulated. According to the beam theory, then expressions of the soil resistance, shear fores and deflection of the pile can be derived.