Abstract: Collection and study on flavonoids of Abrus cantoniensis scavenge capability of oxygen free radical. The flavonoids were extracted with 70% ethanol as the solvent from Abrus cantoniensis with ultrasonic wave and extraction method.;examining scavenging action and ability of deoxidation of flavonoids extracted from Abrus cantoniensis on DPPH· and O₂^-· with Colorimetric method. Total flavanone from Abrus cantoniensis has a scavenging activity on DPPH· and O₂^-·radicals and an evident reduction capacity on Fe³⁺, the ability of clearance is DPPH·>O₂^-·.There is obvious concentrationresponse relationship between clearance and concentration ,When the content of the total flavonone of Abrus cantoniensis was ρ(flavanone)= 0.228 mg/mL,the clearance rate of DPPH· was 50%；When the content of the total flavonone of Abrus cantoniensis was ρ(flavanone)= 0.306 mg/mL，the clearance rate of O₂^-·was 12.57%. Free radical scavenging ability overall strength is DPPH·>O₂^-·. The flavanones evident reduction capacity on Fe³⁺ was increased by the concentration.

Key words: Abrus cantoniensis, flavanone, ultrasonic extraction, in vitro, antioxygen free radical activity