Abstract: The antibacterial activity of the fermentation supernatant of Bacillus velezensis 2L-1 against plant pathogenic fungi was determined through toxic medium method. The control effect of strain 2L-1 on sesame stem rot and sesame Corynespora leaf spot, as well as its growth-promoting effect on four crops, were determined through pot experiments. To clarify the biocontrol effect and mechanism of strain 2L-1, the enzyme activity during its antagonistic process and its growth-promoting characteristics were tested.Whole genome sequencing and prediction of secondary metabolite gene clusters were performed on strain 2L-1. The results showed that in the toxic medium method, the inhibitory rates of ten times dilution of the fermentation supernatant on pathogens of the sesame stem blight and the sesame Corynespora leaf spot were 91. 51% and 83. 78%, respectively. This strain can secrete cellulase, protease, and xylanase, and has the characteristics of dissolving phosphorus and producing siderophores. No activities of glucanase and chitinase was detected in the dish. In the potted experiment, the control effect of this strain on sesame seedlings was 45. 37% when it was inoculated before Macrophora phaseolina, while the control effect was 29. 71% when Macrophora phaseolina was inoculated before this strain on sesame seedlings; When the strain inoculates sesame seedlings before Corynespora cassiicola, the control effect was 25. 82%, while when Corynespora cassiicola inoculates sesame seedlings before the strain, the control effect was 33. 64%. The 1 × 10~8 cfu/mL bacterial suspension of strain 2L-1 had a significant promoting effect on the plant height, fresh weight, and dry weight of the tested crops. The plant height of the tested crops increased by 26. 52% to 36. 26%, the fresh weight of the aboveground parts increased by 71. 43% to 113. 64%, and the dry weight increased by 50. 00% to 128. 57%. Twelve secondary metabolite gene clusters were predicted in the genome of this strain. It can be seen that strain 2L-1 has potential applications in sesame diseases prevention and growth promotion.