Abstract: Vegetation index as an important physical parameter indicating the plant growth was widely used in vegetation mapping and vegetation classification. In order to understand the distribution patterns of alpine vegetation in the Wenquan area of the QinghaiTibet Plateau, the field survey data from 283 samples and MODIS EVI and DEM was applied to determine EVI temporal characteristics and terrain characteristics of various vegetation types (including elevation, slope grade and slope direction), and these characteristics data were used to establish the relative knowledge database. The established database was used to map vegetation classification of the Wenquan area by using decision tree approach. This study showed that the overall accuracy and kappa coefficient was 72% and 0.60, respectively, and this implied that the decision tree approach was effective to classify and identify the alpine grassland type by EVI data with similar phenological characteristics.