"Riparian ecotone" refers to the functional-frontal-zone between an internal water-ecosystem and land-ecosystem, and riparian ecotones-as the sinks, sources or transformers of soil organic matter-contain the interference from the uplands, lowlands and aquatic zone. Riparian ecotones had played a critical role in regulating the conponents of chemical composition between terrestrial and aquatic zones. In addition, they have also had a significant effect on maintaining biodiversity, preventing pollutants from the land ecosystem entering the aquatic zone, and improving water quality or any other aspects. Soil offered essential nutrient substance for the growth of vegetation. The decomposition of organic matter and the transformation of nutrient substances in the soil have not only influenced the growth of vegetation but have also had an indirect effect on the quality of the water. The partial involvement of soil enzymes throughout process of soil organic matter decomposition and synthesis, has influenced all the biochemical reactions of soil, directly or indirectly, and has had a great impact on material circulation within the ecological system. Much debate has focused on the variation in soil enzyme activities with different vegetation types, e.g., farmland, forest land and wetland. Riparian ecotones have diverse vegetation types, complicated by the variation in soil properties aggravated by periodic flooding conditions. However, studies aimed at soil enzyme activity under different vegetation communities in riparian ecotones have been scare. In the riparian ecotones of the Lijiang River, soil water-soluble chemical composition, four types of soil hydrolase(glycosidase, chitinase, leucine aminopeptidase and phosphatase)and two types of oxidoreductase (phenol oxidase and peroxidase) were measured in relation to three vegetation types: mosses, herbs and shrubs. The relationship between the soil properties and enzyme activities was also studied. The results showed:(1) that the activity of soil glycosidase and phenol oxidase under mosses was significantly greater than that under herbaceous and shrubs;(2)that the soil glucosaminidase activity under shrubs was significantly higher than that under mosses and herbs;(3)that the peroxides activity under herbs was significantly higher than that under mosses and shrubs; and that there was no obvious difference in the activity of leucine amino peptidase among the three vegetation types. Among the six enzyme activities examined, soil water content was positively related to the activity of glucosidase and phenol oxidase, and negatively related to the activity of glucosaminidase and alkaline phosphatases. Soil organic carbon and readily oxidizable carbon were negatively associated with glucosidase and phenol oxidase, but positively associated with glucosaminidase. Dissolved organic carbon in soil was positively related to the activity of both glucosidase and phenol oxidase. In short, there were differences between different types of soil enzymes under different vegetation types in riparian ecotones, and soil water content and soil organic carbon significantly influenced the change in soil enzyme activities. In riparian ecotones enriching the plant diversity can accelerate soil ecological processes. The difference in soil enzyme activities under different vegetation communities was not only related to the vegetation types, but also to the micro-topography and spatial heterogeneity of the soil properties in riparian ecotones. Future research on soil enzyme activities under different kinds of vegetation types in the soil of riparian ecotones of the Lijiang River should incorporate long-term control-tests.