Abstract: We extracted polyphenols from lilac (Syringa oblate) and tested their antioxidant activity. The optimal extraction conditions were found to be ethanol concentration of 55%, material/liquid ratio of 1∶50, extraction temperature of 70 ℃ and extraction time of 50 min. Under these conditions, the yield of lilac polyphenols was (1.73±0.05) mg/g. With the biological activity tracking method it was found that the polarity of the strongest antioxidant fraction in lilac polyphenols was weak, the total reducing capacity was 0.64±0.01 and DPPH free radical scavenging capacity was (79.44±0.67)% when the concentration of the sample solution was 70 μg/mL. The study revealed that the capacity of the strongest antioxidant fraction of lilac polyphenols was increased after the treatment by artificial gastric solution, while decreased after the treatment by artificial intestinal solution.