Abstract: For studying the slope erosion type changing process, simulated rainfall was applied by placing rare earth elements on different soil depth across the slope. The results indicated that the main erosion type was sheet erosion in the beginning of rainfall, and serious erosion happened after rill erosion appeared. The percentage of sheet erosion to the whole erosion was about 30% and the percentage of rill erosion was about 70%. The erosion of the first layer was the biggest on unit depth, and then decreased with the depth of soil. Therefore, according to the changing trends of the sheet erosion contribute rate and the rill erosion contribute rate, the erosion on slope could be divided into three phases: main sheet erosion phase, rill erosion developing phase and rill erosion stabile phase. Therefore, REE-INAA method could accurately quantify the processes of soil erosion.