An unconditionally stable algorithm for the numerical integration of poroelastoplastic constitutive relations is analysed in detail in this paper. The constitutive equations of poroelasticity are interpreted according to the micromechanical considerations. The “effective stress” formulation is also introduced. The tangent moduli resulting from this integration algorithm are obtained by consistent linearization of the poroelastoplastic constitutive equations. The algorithm is applied to Gurson’s constitutive model and explicitly extended to the composite material. The tensile test simulation is solved in the ABAQUS general purpose finite element program. The finite element results are compared with those obtained from the experimental study.