The interaction of the soil with the structure has been largely explored with the assumption of material and geometrical linearity of the soil. Nevertheless, for moderate or strong seismic events, the maximum shear strain can easily reach the elastic limit of the soil behavior. Hence the nonlinear effects may change the soil stiffness energy dissipation into the soil. Consequently, ignoring the nonlinear characteristics of the dynamic soil-structure interaction could lead to erroneous predictions of structural and/or geotechnical response. The goal of this work, therefore, is to implement a fully nonlinear constitutive model for soils into a numerical code through Sigmoidal 4 non-linear constitutive model in order to investigate the effect of soil nonlinearity on dynamic soil pile interaction using the finite difference software called FLAC3D. The implemented model was first numerically verified by comparing the results with what is done laboratorically for the same soil properties. Afterward, a parametric study was carried out for different frequency variation in such a way that some extensions were made just beyond the fundamental frequency after determining it to characterize nonlinear effects. Different features of the dynamic soil-pile interaction were investigated after wards: the variation of settlement of the pile head with frequency, the characteristics of pile deformation with the pile length, the distribution of axial force with frequency, the variation of skin friction with frequency, the Characterstics of axial force distribution with the pile length and that of skin friction with pile length was investigated. It was shown that a point where the fundamental frequency of the structure and the natural frequency of the soil were coincided simultaneously, the response of the pile was found to be maximum and it was also the point where direction of increment was changed. Also the Characterstics of axial force distribution and skin friction were reversed to each other with frequency