Abstract: Taking the Sonchus arvensis L.as test material, the process of subcritical water extraction of total flavonoids was optimized by one-factor test combined with response surface methodology, and the antioxidant activity of crude flavonoids extracts was also evaluated, in order to provide reference for the further development and utilization of S.arvensis L..The results showed that the optimal extraction conditions were extraction temperature 127 ℃,extraction time 16 minutes, liquid-solid ratio 24∶1 mL·g^-1,and the stirring rate 120 r·min^-1.Under this condition, the total flavonoids yield was 39.02 mg·g^-1,which was highly consistent with the predicted value of 39.06 mg·g^-1,indicating that the extraction process was stable and feasible.Crude total flavonoids extracts obtained under the optimal conditions showed good Fe²⁺ chelating capacity and Fe³⁺ reducing capacity, indicating that S.arvensis L. could be used as a material source of natural antioxidants.