Abstract: With burdock root as materials, determining total flavonoids of burdock root for their potential antioxidant activity.Therefore, the antioxidant activity assays included DPPH free-radical scavenging capacity, hydroxyl radical scavenging activity, total antioxidant capacity, reducing power, Fe2+ chelating ability, the inhibitory activity toward lipid peroxidation and protective effect on DNA oxidative damage.Total flavonoid contents were also determined.Total flavonoids of burdock root exhibited strong DPPH free-radical scavenging (IC50=15.7mg/mL) activity, hydroxyl radical scavenging activity, metal chelating ability, total antioxidant capacity, reducing power and inhibitory activity toward lipid peroxidation (34μg/mL) .Meanwhile, total flavonoids of burdock root had also a protective effect on K562 cell DNA oxidative damage.Furthermore, these results demonstrated that potential antioxidant activities of burdock root, providing scientific support for the empirical use of burdock root as an antioxidant for diseases caused by reactive oxygen species.