Rill erosion and inter-rill erosion of two soils, cultivated Acrisol and Cambisol derived from Quaternary red clay and red sandstone respectively, were studied by using simulator rainfall in subtropical China Results from experimental plots which are similar to local fields planted with peanut and Sweet potato etc., show that without outside in-flow the soil losses resulted from rill erosion are similar to that from inter-rill erosion, and that soil rill erosion rate is closely related to soil characteristic and volume of the in-flow. Effects of the same in-flow on the two types of soils are very different. Inter-rill erodibility factor K of the two soils, 0.1646 and 0.1362(10^-6gsm^-6),were also calculated respectively by using some relative equations in WEEP model.