Abstract: The floristic composition and the species diversity of the Castanopsis eyrei community in Gutianshan National Nature Reserve of Zhejiang Province were analyzed.The results show that there are 133 species (including varieties)of 86 genera and 49 families in total,including 6 species of 5 genera and 4 families in Peridophyte,2 species of 2 genera and 2 families in Gymnospermae and 125 species of 79 genera and 43 families in Angiospermae.The floristic elements are complex,and the total rate of tropical distribution is very high.The community has a high diversity of family,genus and species,has a great variety of plants whose composition is complex.In the vertical structure of community,the species diversity decreases from shrub,tree to herb layer.The species richness and species diversity index of the tree layer and shrub layer are obviously bigger than those of the herb layer.