Abstract: This paper presents the principle that the shear displacement method is extended to analysethe nonlinear shear displacement of soil around the pile under the pressure of foundation.And theclosed solutions of the nonlinear displacement are obtained with the stepwise linear and the hyperbolicmedel of shear stress-strain relations of soil respectively. The quasi-plastic shear displacement coeffi- cients and the quasi-elastic-plastic flexlbility matrix of the soil are given, which provide the basis ofnumerical methods for analyzing nonlinear interaction of pile-soil-foundation. The calculated results forsome typical cases show that the methods are reasonable and effective.