The sediment samples collected from the different sites of the Lake Taihu, 2006 were cultured on traditional nutrient medium. 603 bacteria strains were separated with 40 different morphological features, and were grouped into 4 clusters and 51 subclusters at the level of 0.75 with numerical classified based on the unweighted pair group method with arithmetic averages (UPGMA) algorithm. Based on the partial sequences of 16SrDNA (540bp) analysis, the bacteria strains sample chosen from each subclusters randomly were ranked into Firmicutes, Actinobacteria and γ-Proteobacteria three groups, and closely related to Bacillus, Paenibacillus, Micrococcus, Arthrobacter, Dietzia and Pseudomonas genera. The dietzia genera was reported in the sediment of freshwater lake in China for the first time.