Runoff is the main power causing soil erosion.So,an accurate estimation of runoff in differentrainfall and underlying surface conditions is the key to predict soil erosion and control soil and water loss.The SCS-CN model developed by Soil Conservation Service of USDA is applied to the simulation of surfacerainfall-runoff processes in the Chaohu Lake basin.With the support of ArcGIS 9.2software,annual surfacerunoff in the basin from 2002to 2006is estimated and runoff yield capability under different land cover typesis analyzed.Results show that there is a greater inter-annual variation of runoff in the basin and runoff depthranges from 591.323to 1557.136mm.The runoff yield capabilities under different land cover types may beranged in the order of urban land>paddy field>unused land>dry land>rural areas>grassland>forest land>scrubland.