Abstract: In this paper the main achievements gained from the study on the change of sand texture during its deformation are summarized first, and then an incrementally nonlinear model different from the existing elasto plastic ones is presented. In the formulation of this model both the reversible and the irreversible deformation due to the change of mean normal stress and normalized shear stress, the turn of stress path and the rotation of principal stress axis have been taken into account. The computed examples show that the proposed model can successfully simulate the softening of dense sand due to dilatancy and the undrained instability of loose sand under monotonous loading, the accumulation of residual strain and pore pressure during repeated loading and also the liquefaction induced by the change of Lode’s angle and the rotation of principal stress axis.