Abstract OBJECTIVE To investigate the effect and mechanism of flavonoids from Sophora flavescens Ait. on testicular tissue damage in male mice induced by local heat stress in the scrotum. METHODS TCMSP database was used to screen the targets of flavonoids in Sophora flavescens Ait., and the bioinformatics analysis was performed on the target. The mouse model of scrotal heat stress was used and the flavonoids of Sophora flavescens Ait. was used for intervention. The sperm density and sperm aberration rate of mice in each group were measured, and the morphological changes of testicular tissue were observed. Tumor necrosis factor-α (TNF-α) and interleukin 17(IL-17) mRNA and protein levels in testicalar were detected of by q-PCR and Western blotting. Na+-K+-ATPase, Mg2+-ATPase, Ca2+-ATPase, lactate dehydrogenase(LDH), sorbitol dehydrogenase(SDH) activity, malondialdehyde (MDA), NO, TNF-α level and the content of testosterone in serum were detected in tissue homogenate. RESULTS Heat stress could lead to the decrease of sperm density and increase of aberrant sperm, the obvious thinning of testicular spermatogenic epithelium, the decrease of cell level and quantity, the significant decrease of ATPase, LDH, SDH activities, and the increase of MDA, NO content, TNF-α and IL-17 expression in testicular tissue. After the intervention with 250, 500 mg·kg-1·d-1 flavonoids of Sophora flavescens Ait., the quality of sperm and the damage of testicular tissue morphology were improved. The level of TNF-α and IL-17 in serum and testicular tissue were decreased, and the activity of ATPase, SDH and the level of testosterone were increased. CONCLUSION The mechanism of flavonoids of Sophora flavescens Ait. is through inhibiting the inflammatory factor TNF-α and IL-17 levels, improve the anti-lipid peroxidation ability and inhibite the role of NO, enhance the activity of energy enzymes in spermatogenesis, improve the level of serum testosterone, and improve the reproductive disorders caused by heat stress.