Abstract: To select the optimal compound ratio for amino-oligosaccharide and benzothiazolinone to control tobacco bacterial wilt, the toxicities of different mass proportions of amino-oligosaccharide and benzothiazolinone against R. solanacearum strain CQPS-1 were determined by a filter paper approach. The growth promotion and control efficacy of the optimal compound ratio of amino-oligosaccharide and benzothiazolinone were investigated by indoor pot and field tests. The results showed that when the compound ratio was 1∶3, the mixture of amino-oligosaccharide and benzothiazolinone (abbreviated as compounded agent) had the highest toxicity against the strain CQPS-1, which was slightly higher than that of benzothiazolinone, and their EC₅₀ were 22.05 and 23.69 mg/L, respectively. The results of the pot experiment showed that the control efficacy of the compounded agent was higher than that of benzothiazolinone or amino-oligosaccharide alone. The results of the field experiment showed that the compounded agent was able to improve the agronomic traits and promote the development of tobacco root, and the growth promoting effect was better than that of amino-oligosaccharide or benzothiazolinone. Compared with the control group, plant height, stalk circumference, middle leaf length, middle leaf width and leaf area at the topping stage were significantly increased by 10.42%, 8.57%, 14.93%, 10.30% and 26.55%, respectively. The control efficacy of the compounded agent was better than that of the single agent on tobacco bacterial wilt. The relative control efficacies of the compounded agent at the early (15 days after application) and peak (48 days after application) stages of infection were 78.06% and 73.68%, respectively, which were higher than those of benzothiazolinone (70.54% and 64.76%) and amino-oligosaccharide (44.40% and 42.05%). Therefore, the combination of amino-oligosaccharide and benzothiazolinone could enhance the antibacterial activity and control effect of benzothiazolinone.