Abstract: A series of conventional triaxial tests, isotropic compression tests and complex stress path triaxial tests are conducted to investigate the particle breakage characteristics of rockfills, which are evaluated quantitatively by using the relative breakage B_r. The plastic work in the progress of triaxial tests under different stress paths is compared. The relationship between particle breakage and plastic work done by the mean stress p or generalized shear stress q under different stress paths is analyzed. The results show that the particle breakage of triaxial tests under complex stress paths which simulate the stress paths of rockfills during the progress of construction and impoundment of earth-rockfill dams is much less than that of the conventional triaxial tests. The relationship between plastic work and relative breakage under different stress paths tends to show a unique curve, which can be well fitted by the power function. The plastic work done by the generalized shear stress q accounts for a dominant proportion of all work in the conventional triaxial tests. And in the complex stress path triaxial tests, the proportion of plastic work done by the mean stress p to that done by the generalized shear stress q is different from case to case.