Abstract: The soy isoflavone was extracted by ethanol extracting methods, acid hydrolysis extracting method and supercriticalfluids CO2 extracting method, and the extracting efficiency of the three extracting methods were compared. The antioxidant capacityand stability of soy isoflavone and soy isoflavone aglycone were compared too by the the experiments of mensurating the abilityof scavenging•OH ,reducing power and antioxidant activity to lard.

Key words: soy isoflavone, extracting, antioxidative activity, stability