Abstract: Research on plant species diversity and its correlation with environmental factors have been one of the important contents in geography and ecology. By means of investigation method, the statistical analysis and calculation on species number of arbor, shrub and herb in 23 plots in Baotianman Nature Reserve on south slope of Fu’niu Mountain, as well as Margalef and Shannon-Wiener indexes of arbor were carried out. On these bases, the main environmental factors influencing on species diversity were screened out by principal component analysis (PCA),and the Pearson correlation was used to analyze the correlation between plant diversity and environmental factors. According to the PCA, the main ingredient was not clear in explaining the spatial variation pattern of vegetation species diversity. However, correlation analysis results showed that the correlationship between soil properties and plant diversity was the most strong, followed by topographic elements and meteorological elements. Among the 15 environmental factors, there was the most significant relationship between soil organic matter and plant diversity. For the three plant type, herbage has the most strong correlation with environmental factors, then arbor and shrub.