Abstract: In order to explore the mechanism of hesperetin inducing tobacco plants' resistance to bacterial wilt, hesperetin with the best control effect against tobacco bacterial wilt was screened from 12 flavonoids, and the accumulation of H₂O₂, the activities of leaf defense enzymes, and the expression of genes related to disease resistance were analyzed and determined. The results showed that hesperetin had no antibacterial effect at a low concentration of 1 mmol/L, but had obvious effect on inducing tobacco plants' resistance to bacterial wilt. Hesperetin irrigation caused H₂O₂ deposition, significantly increased the activities of peroxidase (POD), phenylalanine lyase (PAL) and the content of secondary metabolites phenols and flavonoids. In addition, the expression of resistance genes NtPR1a, NtNPR1, and NtPAL was up-regulated, thereby improving the resistance of tobacco plants to bacterial wilt. Therefore, hesperetin could be used as bacterial wilt inducers to effectively control the occurrence of bacterial wilt.