Abstract: In order to explore suitable microbial strains for alleviating soil acidification and develop new acid soil conditioners, a Pseudomonas fluorescens strain SSW-11 was evaluated from acidified tobacco-planting soil in Enshi County by in situ cultivation. Pot and field experiments were conducted to evaluate the effect of root irrigation with the fermentation broth of the strain on acidified tobacco-planting soil. The results showed that: 1) SSW-11 alleviated the soil acidification caused by composite organic acids and composite fertilizers, accompanying with an increase of soil pH by 0.18 on average. 2) Within 42 days after the root irrigation treatment, SSW-11 significantly increased soil pH by 0.47 on average during the fast growing stage. 3) SSW-11 significantly reduced the incidence and disease index of tobacco bacterial wilt at the mature stage, and its control efficacy on tobacco bacterial wilt reached 52.01%. Pseudomonas fluorescens SSW-11 showed satisfactory effects on alleviating soil acidification and controlling tobacco bacterial wilt.