Abstract: In order to understand the characteristics of grassland vegetation community in southern China, the species composition and structure of grassland vegetation with different slope orientation in Guangnan county,Southeastern Yunnan Province were analyzed by Margale richness index, Simpson dominance index, ShannonWiener index and Pielou evenness index. The results showed that :(1) A total of 84 species of herbaceous plants were recorded in the field survey, belonging to 31 families and 76 genera. Among them, the grasses had the largest number of species, 22 species belonging to 19 genera;(2) the dominant species of different vegetation structures have nothing to do with the slope conditions, and the number of species in herbal vegetation under different vegetation structures is richer;(3) the influence of slope aspect on vegetation evenness was small, but the influence on richness and dominance was obvious. In general, different slope directions had a relatively small effect on the species composition of herbaceous plants under different vegetation community structure, but had a great effect on the distribution and species diversity of herbaceous plants under different vegetation community structure.