The filtration rate of soils on Loess Plateau is different in varrious regions.In accordance with the steady infilatrition rate of the soils, Loess Plateau is divided into five regions of grade-Ⅰ and four regions of grade-Ⅱ.The regions of the highest filtration rate are located in Ziwuling, Liaoshan, Huanglongshan and the southern sector of Luliangshan Mt.on the central of the Plateau generally covered by secondary broadleaf forests of abores or brushes, the soil surface is commonly covered by a thick layer of litters;with good structure and greater porosity, the soils are the highest in filitritation rate.The regions of higher filtration rate include Hujialing, Dongzhiyuan of Gansu, Yijun, Zhouzhi, Meiaian and Changan of Shaanai, and Yicheng, Quwo of Shangi.