Runoff is the main factor responsible for soil erosion,so an accurate estimation of runoff is the key to predictand control soil erosion. The Soil Conservation Service curve number (SCS-CN) method is widely used for predicting directrunoff from rainfall in the area withoutobserved runoff data. Using data of 153 runoff events from 6 experimental plots with three landuse types of millet,alfalfa,and sorghum on the Loess Plateau,the applicability of SCS-CN method is validated and the parameters are optimized. Results indicate thatthe accuracy of runoff prediction by the SCS-CN method with optimized^λand CN₂ values is better than thatof the standard CN method. The optimized^λvalue is 0. 01 and the CN₂ values are 74,74,and 72 for millet,alfalfa,and sorghum,respectively.