Soil erosion is a complex phenomenon involving the detachment and transport of soil particles, storage and runoff of rainwater, and infiltration. The relative magnitude and importance of these processes depends on a host of factors, including rainfall intensity, surface roughness, subsurface soil water pressure, and so on. Thus, in our study, the soil erosion results of a series of experiments were reported in the form of a volume index. Different rainfall intensity in relation to the erosion rate was investigated for the chronological phenomenon and more insight and detail were got to improve estimation of eroded volume of the slope surface. The results show the surface runoff by rainfall is the key factor in producing the soil sediment. And a sequence of rainstorms of increasing intensity on an initially smooth surface cause high soil loss rate,but which will be slowed down with the aggravation of surface roughness and the formation of rills. The highlight is the use of 3D fitting model by which the interaction and function among rainfall intensity, duration, and soil yield sediment is investigated.