Abstract: Soil compaction occurs in agricultural ecosystems commonly. The effect of soil compaction not only has negative effect for agriculture but also could increase the potential pollution of surface water. In order to clarify the movement of soil water and solution in compacted soil and the impact of compaction on agricultural production and eco-environment, an improved model with two parameters was proposed, which relies on an existed soil compaction model. Four undisturbed soils were used in centrifugal procedural to test the improved model. Results show that the improved model fits the data better, and the performances of improved model are better than that of the L model. Although there is no remarkable difference in the theories and performances between improved model and Assouline model, fewer parameters and simple representation are the advantages of the improved model. Meanwhile, the improved model will provide important reference to the study on bulk density changes during soil water characteristic measurement.