Abstract: On the basis of the results of large-scale triaxial tests on typical rockfills for the construction of dams,their shear behaviors under different void ratios or confining pressures including the relationship of(σ1/σ3)-εa and εv-εa,and relationship of dilatancy ratioζ and plastic shear strain εsp were analyzed.It was shown that ① For the rockfills with determined particle grading,the conversion between shear dilatancy and shrinkage of the samples depended upon a critical initial void ratio(e0)crit and critical consolidation pressure(σc)crit;② The shear dilatancy ratioζf at the failure of the samples could be a criterion by which whether shear dilantancy appeared or not could be judged.By means of the nonlinear fitting of the results of triaxial tests,the relationship of(σ1/σ3)-ε a and the relationship of εvp-εsp were described by a uniform formulation,and then the equation of stress-dilatancy and the formulation of dilatancy ratioζf at the failure,which depended upon the initial state of the samples,were proposed respectively.So a criterion was established on the formulation of shear dilatancy ratio ζf which depended upon the initial void ratio e0 and confining pressure σc of the samples.