The triaxial wetting test in single line method of rockfill materials with different initial void ratio was carried out, and the varies of wetting deformation with the confining pressure, stress level and initial void ratio were analyzed. The test results show that the axial and volumetric wetting deformation decreases with the decrease of the initial void ratio under the same confining pressure and stress state. Based on the test results, it can be found that the initial void ratio has little influence on the dilatancy law of wetting stress, and the logarithmic wetting dilatancy equation can be used to describe the wetting stress dilatancy relationship under different initial pore ratio conditions. In addition, the model for the axial wetting deformation with the consideration of initial void ratio and stress state was proposed by modifying the empirical exponential model. After that, the equation for the volumetric wetting deformation was derived by the stress-dilatancy equation. Finally, the rationality of the proposed model was validated according to the comparison with test results.