Based on an analysis of effect of the initial pore ratio,effective consolidation pressure and dynamic stress ration on the axial plastic cumulative deformation of the silty sand and a consideration of the effect of the dynamic partial stress level and the initial consolidation pressure of the silty sand, an explicit model of which parameters were of physical significance was build up to calculate the axial plastic accumulative strain of silty sands under cyclic loading. Parameters of the explicit model were determined by undrained cyclic triaxial tests on anisotropically consolidated Shanghai silty sands and validity of the model was verified by the cyclic tested data.