A tank experiment to study the rainfall characteristics, degree of slope and kinds of crops iri relation to erosion of the Szechwan purple brown soil was carried out on the experimental farm of the University of Nanking in Chcngtu during the period from 1941 to 1945 inclusive. The text consists of the results, of four years only, that of the first vear being used for reference. There were four wooden tanks altogether; each tank was 1.8 meters long, 0.35 meters wide, and 0.33 meters in depth. They were made water proof; and aceessory parts for receiving runoff and soil loss were appropriately provided. A kind of the common purple brown clay soil was put in the four tanks which were placed on.brick fbundations having slant tops of 5,10,30 and 30 percent slopes respectively. There was a rain gauge between the two tanks on each side.when there was rain, measurements of rainfall, runoff and soil loss were made at 24-hr. intervals.