Abstract: With the widespread use in practical engineering projects (such as high earth-rock dams), the particle breakage becomes an important aspect in studies on coarse-grained materials. Through the triaxial tests of the coarse-grained material, the particle breakage under the isotropic consolidation, peak strength and different stress level conditions are studied. The influences of drying and wetting on particle breakage are analyzed. It is indicated that the power function is fit for the relation between the particle breakage ratio and the confining pressure under the isotropic consolidation, and is also fit for the relation between peak internal friction angle and the corresponding particle breakage ratio; the particle breakage ratio will speed up to increase with the increase of stress level under a certain confining pressure, and increase with the increase of confining pressure under a certain stress level; the relation between the particle breakage ratio and the stress level may be unitary under different confining pressures; with the same stress state, the particle breakage under wet state will be larger than that under dry state, and the difference is mainly determined by softening coefficient of material. At the same time, the theoretical analysis is done for these results, a new method to estimate the particle breakage value is proposed, and the relation between the influence on breakage of dry and wet states and the material softening coefficient is also discussed.