Abstract: Based on the results of large-scale triaxial test of rockfills, an exponential formulation of the nonlinear strength envelope is presented. When the nonlinear strength criterion is introduced to determine the shear and volume yield surfaces, a new elasto-plastic constitutive model is herein developed for reproducing practical engineering behaviors of the rockfills. The numerical simulations for the various stress-path test are performed in a developed program with the proposed model and Yin’s model. It is shown that the proposed model can realistically describe the strength and deformation characteristics of rockfills subjected to some complex loading conditions.