Abstract: Rockfill materials are widely used in civil engineering, such as dams, railways, and airport foundations in mountain areas. Significant wetting deformation may affect the serviceability or even the safety of rockfill infrastructure. Particle breakage is an important reason for wetting deformation. However, the relation between particle breakage and wetting deformation remains unclear and further study is necessary. The discrete element method was used to simulate single-line and double-line wetting tests, and the differences between the two methods were discussed. The relationships between particle breakage characterized by Hardin index, strain and friction energy were analyzed. Furthermore, the effect of wetting path, particle shape and softening coefficient on wetting deformation were investigated. The preliminary results showed that the wetting deformation increased with the stress applied, and larger wetting deformation was observed with the single-line method. During the loading process, particle breakage mainly occurs at the corners of particles. Angular particles experience more breakages and larger wetting deformation under one-dimensional compression than rounded particles. Moreover, the relationship between the Hardin index and friction energy dissipation is affected by the wetting path, while the relation between Hardin index and the strain is unique and depends exclusively on the initial density and intrinsic parameters of the material.