Abstract: To study the effect of soil deformation, the soil-water characteristic curves (SWCC) are tested using VJ Tech consolidation apparatus with the initial void ratio taken as the deformation index. The test results show that in low suction range the effect of the initial void ratio on SWCC is significant, while in high suction range the effect is not remarkable. By introducing the void ratio into the model parameter related to the air entry value, a new soil-water characteristic surface (SWCS) model is proposed based on the Fredlund-Xing model so that the new model can be utilized to predict the varied coefficient of permeability during soil deformation. The new model is also applied to the seepage analysis of a soil dam with core wall, and it is found that for different degrees of compaction, the seepage flow flux is dependent on the saturated coefficient of permeability or is proportional to e³/(1+e).