Abstract: Anisotropic plasticity and structure,together with their evolution laws were considered based on Wheeler’s S-CLAY1 model.The traditional constitutive model was developed to fit for K0 consolidated structured soft clays,consistent with the author’s previous works.The rotational limit line was introduced to the rotational hardening law and a parameter b was added to the model to reflect the evolution of anisotropy.The effect of rotational hardening on the behavior of K0 consolidated structured soft clays was analyzed and the initial value of anisotropic parameter could be obtained from the common laboratory tests.Two typical soft clays,Whenzhou clay and Bothkennar clay,were chosen to be calculated under tiaxial conditions.The importance of the rotational behavior of yield surface was indicated by the comparison of the calculated and tested results.At the same time the method to obtain the parameter b as well as its range was also dicussed.