A lot of research about soil erosion similarity have done and obtained rich achievements. However, strictly speaking, it need to do a lot of deep study about to establish the ratio scale model of soil erosion, the problems unsolved include of does not establish the similar equation system about soil erosion and sediment yield entities simulation, we did some experiment, the date shows: the raindrop speed mainly at 0.6-5m/s in 10min, the wave crest was 1m/s and 4.2m/s. At the same times, the 0.125mm grain diameter raindrop speed was about at 0.6-1.4m/s, the 0.25mm grain diameter raindrop speed was about at 1-1.4m/s, the 0.375mm grain diameter raindrop speed was about at 1-1.4m/s, the 0. 5mm grain diameter raindrop speed was about at 1-3.4m/s, the 0.75mm grain diameter raindrop speed was about at 3.4m/s, the 1mm grain diameter raindrop speed was about at 4.2m/s, the 1.25mm grain diameter raindrop speed was about at4.2-5m/s, the 1.5mm grain diameter raindrop speed was about at5m/s.