Bacterial diversity in the sediments of Taihu Lake was studied by using traditional nutrient medium (NM) and 10-fold dilution of traditional nutrient medium (DNM). Results showed that the amount of the bacteria cultured on DNM was 3-5 times higher of those on NM. The similarities of 16S rRNA gene sequences (about 500 bp of 5'-end) of 164 isolates were analyzed. The results indicated that the different concentrations of nutrient medium did have effects on the dominant bacteria. On traditional nutrient medium, the dominant bacterial groups were gamma-Proteobacteria (35.1%), Actinobacteria (24.5%) and Firmicutes (22.3%). Most of the bacteria isolated from NM were closely related to genera Pseudomonas, Bacillus and Archrobacter. However, the dominant bacterial groups isolated from DNM were Actinobacteria (27.1%), Firmicutes (25.7%), alpha-Proteobacteria (21.4%) and gamma-Proteobacteria (15.7%). Bacillus-related strains were predominant bacteria. The conclusion is that using different concentration media will assist to isolate more and comprehensive bacteria from the sediments of Taihu Lake.