Abstract: To evaluate the effects of different soil amendments on the metabolic diversity of microorganisms in tobacco rhizosphere soils and the incidence of tobacco bacterial wilt, field experiments were conducted to study the effects of different soil amendments on soil pH and the metabolic diversity of microorganisms and their control efficiencies on tobacco bacterial wilt. Four treatments were set as following:oyster shell powder, quicklime, plant ash and the control. The results showed that oyster shell powder raised soil pH significantly and increased the carbon source utilization by soil microorganisms(Average well color development, AWCD), the metabolic diversity of microorganisms (Shannon index) and the uniformity of species in soil microbial community (McIntosh index). Principal component analysis indicated that carboxylic acids, amino acids and carbohydrates were the main carbon sources utilized by soil microorganisms, however there were some differences in the carbon source utilization characteristics of microorganisms in soils treated by different soil amendments. The incidence of tobacco bacterial wilt in fields treated by oyster shell powder was the lowest, decreased by 43.33% comparing with that of the control. Pearson correlation analysis suggested that soil pH positively correlated to the metabolic diversity index of soil microorganisms, while negatively correlated to disease incidence. Therefore, the application of oyster shell powder can raise soil pH, promote the metabolic diversity of soil microorganisms and the stability of soil micro-ecology environment, and further achieve better control efficiency on tobacco bacterial wilt.