A fully implicit integration scheme in the bounding-surface plasticity model for cyclic behaviors of saturated clay is presented by modifying the conventional implicit return mapping algorithm. Within the critical state framework

based on the concept of shrinking the elastic region to a point

combining isotropic with kinematic hardening rule and a rotated bounding surface

and introducing a damage parameter representing the remolding of the soil fabric

the model can reflect the initial anisotropy

the cyclic stiffness degradation and strength softening of saturated clay under cyclic loading. Firstly

the numerical simulations of the undrained triaxial tests both for isotropic ( ) and anisotropic ( ) consolidated kaolin clay are carried out with variable strain increments. By comparing with the test data

the rationality

robustness and the accuracy of the new fully implicit integration for the bounding surface plasticity model are verified. Furthermore

the prediction for an undrained cyclic triaxial test on a saturated clay is given

and the cyclic degradation of the stiffness and strength is obtained

which indicates the validity of the computational results.