Abstract: 62 samples collected in Midpiece of Zhongtiao Mountains were classified into 16 associations by Two-way Indicator Species Analysis(TWINSPAN). The characteristics of the plant species diversity of 16 associations were studied by using of the formulas of richness indices(R₁、R₅), Simpson’s indices(λ), Shannon-Weiner’s indices(H′) and evenness indices(E₁、E₅). The results indicated that:The species diversity indices of 16 associations varied according to the site conditions and anthropogenic effects； The order of the species diversity indices of the 16 associations showed the species diversity of the arbor-shrub-herbaceous was significantly higher than that of the herbaceous；differences in community species diversities, which are not only determined by species richness indices, but also have a closer relationship with the evenness indices of respective species, thus can influence their respective contributions to the overall species diversity.

Key words: woody plant community, species diversity, community structure, Midpiece of Zhongtiao Mountains