Abstract: Based on the single-line wetting method, wetting tests on mixed sandstone and slate materials are performed using a middle-scale triaxial apparatus. According to the condition of spherical stress and deviatoric stress, the wetting deformation law of rockfill materials is mainly studied. The test results show that the spherical stress and deviatoric stress are the main influencing factors of wetting volume strain and wetting shear strain respectively. The wetting volume strain and stress ratio shows the linear relationship preferably, and the wetting shear strain and stress ratio shows the power function relationship preferably. According to the results, a wetting model and corresponding parameters are initially proposed. The research results are thought to be helpful for the relevant wetting study of rockfill materials.