Abstract: To explore the content of the main components of the total flavonoids extract from folium of Artemisia argyi(TFEFAA) and its antioxidant activity in vivo and in vitro. In this paper, high-performance liquid chromatography(HPLC) was used to simultaneously determine the content of eupatilin and jaceosidin in TFEFAA, the antioxidant activity of TFEFAA in vitro was investigated with the scavenging rate of 1, 1-diphenyl-2-trinitrophenylhydrazine(DPPH), 2, 2-diazo-bis(3-ethyl-benzothiazole-6-sulfonic acid) diammonium salt(ABTS) and hydroxyl radical and total reducing power as indexes. Caenorhabditis elegans(C. elegans) were cultured in nematode growth media containing 0, 50 and 100 μg/mL TFEFAA respectively. The effects of TFEFAA on heat stress and H₂O₂ oxidative stress of C. elegans were studied. At the same time, the related antioxidant enzyme activity and malondialdehyde(MDA) content in C. elegans were detected. The results showed that the contents of eupatilin and jaceosidin were 0.2% and 0.06% respectively and TFEFAA had a significant scavenging effect on DPPH radical, ABTS⁺ radical and hydroxyl radical, and its IC₅₀ were 96.51, 67.73 and 279.38 μg/mL, respectively. The scavenging ability had a dose-effect relationship with TFEFAA, and it also had a strong total reducing power. 100 μg/mL TFEFAA can significantly prolong the survival time of nematodes under heat stress and H₂O₂ oxidative stress(P<0.01), at the same time significantly increase the activities of superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px) in nematodes(P<0.01), and significantly reduce the MDA contents in nematodes(P<0.05). TFEFAA had good antioxidant activity in vivo and in vitro, and its mechanism may be related to improving antioxidant enzyme activity in vivo. Therefore, TFEFAA would be expected to be developed into a new natural green food antioxidant.