Indoor simulation of rainfall, 1.5 mm min^-1 in intensity was conducted using deionized water on slopes of Lou soil and Cultivated loessial soil, 10°, 15°, 20° and 25° in slope degree, and 5 m and 10 m in shope length,separately. Changes in the slopes caused by each rainfall event were monitored with a 3D laser scanner and analyzed for impact of slope degree on rill erosion, differences between slopes of different soils in rill erosion and their affecting factors. Results show that as the Lou soil is dominated with silt and clay in texture with silt content being 64.12% and clay content 18.42, and the Cultivated loessial soil composed mainly with silt (67.95%) and some clay (14.52%) and sand (17.53%), under the same conditions, rian water infiltration rate was lower, runoff generation earlier and runoff velocity higher in the former than in the latter, and as a result, erosion holes occurred earlier and rills formed more easily in the former. During the rainfall event, higher in volume, the runoff stabilized earlier in the former than in the latter. As the erosion rate was higher in the former, silt yield tended to increase, while it remained almost unchanged in the latter. Comparison between the slopes of two different soils in rill development shows that the rills on the Lou soil slopes were distributed in parallel, while those on of the Cultivated loessial soil slopes looked like wide tree branches.