Abstract: Based on the proposed failure criterion for general geomaterials, an elasto-plastic damage constitutive model in three-dimensional stress space is presented by combining the elliptic-parabolic yielding surfaces, the damage yielding surface and the concept of composite framework for structured soft soils. This model can capture such behaviors as the nonlinear stress-strain, shear dilatancy, damage and strain dependence on the intermediate principal stress for structured soft soil. Besides, it can well describe the stress-strain behaviors of structured soft soils based on the comparisons between the true triaxial test results and the simulations.