Abstract: 【Objective】To investigate control effect of rice straw biochar combined with by Bacillus velezensis B4-7on tobacco bacterial wilt,to make clear enhancement effect of rice straw biochar on tobacco bacterial wilt prevention and control by strain B4-7,so as to provide reference for developing biocontrol product to control the wilt.【Method】Influence of rice straw biochar(1% C,2% C,3% C and 4% C)on inhibition,adsorption and motility of tobacco bacterial wilt pathogen were determined by plate culture method. Pot experiment was conducted to determine the effect of strain B4-7combined with 2% and 5% rice straw biochar(B4-7+2% C and B4-7+5% C)on tobacco growth promotion and control effect on tobacco bacterial wilt.【Result】Different concentrations of rice straw biochar influenced growth inhibition,adsorption and motility of tobacco bacterial wilt pathogen. Compared with the control group,in media of 1% C,2% C,3% C and 4% C of biochar treatments,the number of bacteria in each medium decreased by 8.07%,37.01%,53.74% and69.29%,the motility of bacteria decreased by 28.57%,35.71%,42.86% and 48.57%,and the adsorption efficiency were24.18%,42.42%,64.55% and 81.97%,respectively. Compared with the control group,the plant height,leaf number,maximum leaf length and maximum leaf width of tobacco in B4-7+5% C treatment were increased by 209.36%,27.98%,254.51% and 185.09%. Compared with B4-7 treatment group,the plant height and leaf number of tobacco in B4-7+5% C treatment were significantly increased by 77.52% and 11.74%,respectively(P<0.05,the same below). Compared with the control group,the incidence and disease index of tobacco bacterial wilt in B4-7+5% C treatment were decreased by81.33% and 80.61%. Compared with B4-7 treatment group,the incidence and disease index of tobacco bacterial wilt in B4-7 + 5% C treatment were decreased by 54.82% and 45.29%,respectively,and the control effect was increased by24.85%.【Conclusion】Rice straw biochar can enhance the control effect of B. velezensis B4-7 on tobacco bacterial wilt,and the combination of B4-7 and 5% rice straw biochar forms an effective measure for comprehensive control of tobacco bacterial wilt,which has great application prospect and is worth further popularization and application.