Abstract: The ultrasonic extraction process and antioxidant activity of total flavonids from Polygonum chinense were studied. The effects of four factors on extraction rate for total flavonoids were discussed by single factor experiment including material-liquid ratio,ethanol concentration,extraction time and extraction temperature.The orthogonal experiment showed the optimum conditions were as follows :material-liquid ratio 1 ∶50g/m L,ethanol concentration 50%,extraction temperature 70℃,extraction time 20 min. Under these conditions,the extraction rate of total flavonoids was 4.28%. The results of antioxidation showed that the flavonoids from Polygonum chinense had good reduction ability,and also had significant scavenging activity on DPPH· and OH·,the scavenging rates to free radicals were positive proportional to the flavonoids concentration. The EC50 of scavenging activity to DPPH· was 0.00519mg/m L. The EC50 of scavenging activity to OH· was 0.150mg/m L.