An experiment was carried out in Dianchi catchment,a severely eroded region,in Kunming,Yunnan Province,Southwest China.In the experiment,the technique of ¹³⁷Cs tracer is introduced as a new approach to the study of soil erosion,though it has already been extensively used in this field the world over and yield numerous fruits in the study on deposition,erosion and transportation of silts in the process of soil erosion.The method of using ¹³⁷Cs as soil tracer makes it feasible to study soil erosion on the catchment scale,moreover,it is reliable and time-and labor-saving.The Yun-Gui Plateau,squatting in Southwest China,is one of the most severely eroded regions in the southern part of the country.Owing to lack of historic data,it is hard to predict the mid-long term(ca.50 a) mean soil erosion rate,just by measuring for a short term.In this experiment the technique was used to study distribution of soil erosion intensity in the D ianchi Catchment.Results show that soil erosion rate along a slope followed a decreasing order of mid-slope > lower-slope > upper slope;and among the lands different in land use,cultivated land > uncultivated land.The research also revealed that the average soil erosion rate in the catchment was 1 280 t km^-2 a^-1,and in the category of light erosion.Position in the landform,slope and land use pattern are major factors affecting soil erosion.