Abstract: Given the importance of undergrowth vegetation to plantation ecosystem, this study analyzed the effects of three kinds of understory management measures, including understory preservation, understory removal, and interplanting, on the soil bacterial diversity, community structure and relative abundance under large diameter timber plantation of Cunninghamia lanceolata using high-throughput sequencing technology. The relationship between soil physical and chemical properties and bacterial community diversity were analyzed. The results showed that Chao1, Ace and Shannon indices of soil bacterial communities of understory preservation were higher than those of understory removal and interplanting. Actinobacteria, Acidobacteria and Chloroflexi were the dominant bacteria groups in the soil of C. lanceolata plantation. Compared with understory removal and interplanting, the relative abundance of Proteobacteria, Planctomycetes, Firmicutes and Verrucomicrobia in the soil of understory preservation was relatively high, while that of Actinobacteria, Acidobacteria and Chloroflexi was relatively low. There were significant differences in the relative abundance of Firmicutes, Planctomycetes, Verrucomicrobia, Parcubacteria and Actinobacteria among three understory management measures. The contents of moisture, total nitrogen, total phosphorus, hydrolyzed nitrogen and available phosphorus in the soil were important factors affecting soil bacterial community structure. Soil bacterial diversity indices had significant positive correlation with the contents of total nitrogen, total phosphorus, total potassium, hydrolyzed nitrogen and available potassium in the soil.