Abstract:In this study，daylily samples from four producing areas （Shaanxi，Gansu，Ningxia and Hunan） were used to systematically analyze their flavonoid composition and cellular antioxidant stress activity. Liquid chromatography-mass spectrometry （LC-MS） analysis showed that the types of flavonoid compounds were consistent among samples from different regions，with significant differences in compound contents. Ningxia daylily presented the highest contents of eight major flavonoids including rutin and naringenin，and Shaanxi daylily had the highest contents of kaempferol and luteolin. The flavonoid contents of Gansu and Hunan daylily were relatively low. In cellular antioxidant activity evaluation，flavonoids of daylily from all four producing areas effectively reduced intracellular reactive oxygen species and malondialdehyde contents，improved the activities of superoxide dismutase，catalase and glutathione peroxidase，increased the glutathione redox ratio，and upregulated the mRNA expression of key antioxidant genes，so as to relieve cellular oxidative damage. The flavonoids from Ningxia and Shaanxi daylily showed stronger protective effects on cells. The results indicated that daylily flavonoids had excellent antioxidant activity，which provided theoretical support for the development and application of daylily in the field of functional foods.