Abstract:The Pinus armandii secondary forest in Yuxi Mopan Mountain National Forest Park was taken as study site, the characteristics of vegetation were inventoried, soils were collected and soil biological fertility indexes were measured in laboratory in order to explore the relationship between vegetation diversity and soil biological fertility in the Central Yunnan Plateau in China. The results showed that Mopan Mountain Pinus armandii secondary forest was mixed forests with low plant diversity and dominant species of Pinus armandii, there were 13 families, 15 genera and 15 kinds of vascular plants. With the increase of soil depth, soil organic matter, total nitrogen, alkali solution nitrogen, total phosphorus, available phosphorus and available potassium content, enzyme activity and microbial quantity declined, while pH and total potassium increased under Pinus armandii secondary forest. Principal component analyses showed that soil nutrients, catalase, invertase and microbes well indicated soil biological fertility, while diversity index, dominance index and richness index well reflected vegetation diversity. Pinus armandii forest diversity had significant correlation with soil fertility indexes. The diversity of Pinus armandii forest was greatly influenced by soil fungi, catalase, total nitrogen, phosphorus, total potassium, invertase, potassium bacteria, total phosphorus and available phosphorus.