Abstract: By investigation of the vegetation type, coverage, density of the nine forest stands in Luohan Cliff forestry centre, the species richness, Shannon-Wiener index, Simpson index and Pielou index were used to study the species biodiversity of the forest understory vegetation community. The results show that: 1) The species richness of the plantation understory vegetation is mainly affected by the species richness of herb layer. Among them, Gramineae is the most species, followed by Compositae. 2) Species richness of the understory vegetation of Pistacia chinensis & Robinia pseudoacacia stand and Robinia pseudoacacia stand were the lowest and biggest, respectively. As to Shannon-Wiener index, Pinus thunbergii and Platycladus orientalis pure stands take the first and last position respectively. As to Simpson index, pure Platycladus orientalis forest has the minimum value, while the Pistacia chinensis pure forest has the maximum value.