Taken Liangshan County,one of the key demonstration sites in the fifth initiative regarding soil and water conservation in upper Yangtze River as the study area,we analyzed the changes in ecosystem service values of Liangshan County,and developed comprehensive management practices and related models for assessing ecosystem service values in small watersheds,based on the published service values of Chinese terrestrial ecosystems and local grain yield and market price.The results showed that the land use type changed greatly from 1999 to 2003,as the areas of unused and cultivated lands decreased 36 038.67 hm² and 5 498.50 hm²,and the areas of forest and pasture lands increased 35 614.30 hm² and 5 889.53 hm²,respectively.Under the scenario that the proposed comprehensive management practices were carried out,the total ecosystem service value could increase from 1.37×109 to 1.85×109 Yuan.Except the value of food production decreased 3.31×105 Yuan,the other ecosystem service functions increased significantly but to various degrees.It was also found that only forest and pasture lands played positive roles in enhancing ecosystem service values,up to 89.4%.Their changes were the major reason for the increase of ecosystem service value.The average prediction accuracy of the principal component analysis(PCA)-radial basis function(RBF) model reached 94.8%,indicating that the model accurately reflected the influences of small watershed management measures on the ecosystem service values.