Taking the original triaxial test data as the basis, this study analyzed the relationship between the tangential modulus, or the tangent bulk ratio and the stress state. The corresponding relational expression were proposed, respectively. Then, the two new expressions were introduced into Shen’s elastoplastic model with double yield surfaces to replace the old ones. The triaxial simulated results of rockfill materials showed that the modified model can overcome the disadvantages of using the damage stress ratio to control the final strength, especially the inadequate characteristics of shear dilatation (contraction). And the simulated results of different stress path triaxial tests confirmed the new model can well simulate the strength and deformation characteristics of rockfill.