Abstract: A constitutive model of K0 consolided structured soft clays was developed based on the Modified Cam Clay model.The effects of anisotropy and destructuration of the natural soils as well as shear hardening rule were considered with the rotational yield surface.This model came from the thermo-mechanical constitutive model developed by Collins and then the methods that Asaoka established in the super/subloading yield surface model were used.Three parameters(θn,R and R*) and two evolution parameters(m and a) were added to the Modified Cam Clay model together with the initial structural values which were related to the yield stress ratio and the sensitivity of the soft clays.Significant improvements were demonstrated in the performance of the new model over the traditional constitutive models with experimental evidence from Wenzhou clay and Bothkennar clay.