Abstract: γ-aminobutyric acid (GABA) can effectively promote the growth of crops and has important application value in agricultural cultivation. A GABA-producing strain (T. hamatum YMF1.00247) and the effect of its fermentation broth on promoting the growth and preventing black shank on tobacco were analyzed by pot experiments. The disease resistance mechanism was analyzed by the change of plant defense enzymes. The results showed that the content of GABA in fermentation broth of YMF1.00247 was up to 1.33 g /L. However, the strain did not produce IAA, iron carrier and ACC deaminase. YMF1.00247 fermentation broth significantly increased the plant height, leaf number, stem circumference and middle leaf area of tobacco. Application of 100 mL/plant YMF1.00247 fermentation broth and 1.5 g/L GABA significantly reduced the incidence and disease index of tobacco black shank, with the prevention efficacy at 78.41% and 72.36%, respectively, and improved the enzyme activity of PAL, POD and PPO of tobacco leaf significantly. It was suggested that GABA produced by YMF1.00247 could be the main active ingredient which contributing to the promotion of the plant growth and inducing the disease resistance on tobacco.