Abstract: In order to determine the effect of structure characteristic of red soil on slope erosion, the relationship between aggregate characteristic of red soil and slope erosion was preliminary studied based on the analysis of aggregate stability and the simulated rainfall experiment in field. Six typical red soils were chosen for the study. The results showed that the aggregate stability of red soil was the important factor effecting slope erosion in field. The aggregate characteristic parameter Ka which could quantitatively describe soil erodibility showed a significant correlation with the runoff intensity and sediment-yield intensity. By introducing Ka into the WEPP (Water Erosion Production Project) model, the erosion prediction equation was established with a good correlation coefficient (R2 = 0.86). The equation showed a good prediction performance. The study extends the scope of application of the aggregate stability as soil erodibility index, and provides a new way to revel the erosion mechanism of red soil.