Taihu watershed lies at the core of Changjiang River Delta.For protecting water and soil resources of the Taihu watershed mountainous area,and improving the pertinence of water and soil control,adjusting measures to local conditions,and gaining the best controlling effect at lowest cost.This paper takes Liyang of Jiangsu province in Yili mountains of Taihu watershed as sample,according to the data of field and soil section investigation and maps of geomorphology,soil type and landuse,1 214 sample plots main influential factors(slope degree,height difference,organic matter content,effective soil thickness,soil deadlocked grain content,land use types and soil types)were clustered by group average method based on an analysis of 87 model sample fields.The study area was divided into 6 typical districts,their distributions and their characteristics of water and soil loss of each typical district was summarized and analyzed respectively.Finally,the authors pointed out that it is the key step to divide areas studied into different typical districts according to the causes,which lead to water and soil loss. In the process of actualizing the plan of water and soil preservation,water conservancy,bioengineering,agriculture engineering,social engineering and so forth synthetic measures should be used,thus the waste of manpower,material resources,and financial ability can be avoided.