The impact of interbasin water transfer on environment is very significant. The affected area of the west route scheme of the South to North Water Transfer Project in China (SNWT) is located in the eastern Tibetan Plateau, where the altitude is high with frigid eco-environment. In this article,remote sensing and GIS are applied to analyze the natural environment and the natural environmentindex is established to express the natural conditions of the study area. After the natural environment index is divided into four grades and the features of each grade are analysed, some results are obtained for reference in environmental assessment of the west route of SNWT.