Abstract: To control Pseudomonas syringae pv. tabaci more effectively, pathogen was isolated from the tobacco leaves with typical wildfire symptom in Yibin tobacco planting areas. The isolated pathogen was cultured to observe its morphological characteristics. The pathogenicity of pathogen strains was evaluated via acupuncture inoculation and injection inoculation without needle. The biological characteristics of representative strains pv-xs-y-2 (strong), pv-xt-y-2 (moderate) and pv-gy-y-1 (weak) with different pathogenicity were determined by measuring bacteria growth rate, and the inhibition effects of four bactericides on strong pathogenicity strain pv-xs-y-2 were investigated. The results showed that the morphological characteristics of fourteen strains were consistent with those of P. syringae pv. tabaci, but the pathogenicity was significantly different between strains with the average disease index in the range of 23.33-72.22. Based on the pathogenicity of K326, the fourteen strains were clustered into three groups: strong (disease index 60-72.22), moderate (disease index 34.44-53.33) and weak (disease index 23.33); in which, the strains with moderate pathogenicity accounted for 71.43%. On NA medium, the optimum growth temperature for pathogen was 28℃,at which the OD₆₀₀ values of pv-xs-y-2, pv-xt-y-2 and pv-gy-y-1 were 1.285, 1.105 and 0.977, respectively; the optimum growth relative humidity was 100%,at which their OD₆₀₀ values were 0.694, 0.555 and 0.505, respectively; the optimum growth pH was 7. The data indicated that neutral environment was suitable for the growth of P. syringae pv. tabaci. The inhibition effects of different bactericides on P. syringae pv. tabaci were 3% benziothiazolinone > 4% kasugamycin > 72% streptomycin > 20% thiediazole copper, and EC₅₀ value of 3% benziothiazolinone was 9.401 μg ·mL^-1.