Abstract: In this study， the content of total flavonoids in Parochetus communis was determined using Al(NO3)3\|NaNO2 method. The extraction technology of total flavonoids was optimized through L9 (34) orthogonal experiment. The effect of total flavonoids on scavenging of hydroxyl radicals and DPPH radicals in Parochetus communis was also studied. The results showed that the optimum extraction parameters were as follows: The volume fraction of ethanol was 75%， extraction temperature was 75℃， ratio of solid to liquid was 1∶40 (g·mL-1)， and extraction time was 150 min. Under such condition， the average content of total flavonoids was 1.543 mg·g-1， and the scavenging effect of total flavonoids on ·OH and DPPH· were 42.59% and 60.40% respectively， implying such material can effectively scavenge ·OH and DPPH·.

Key words: Parochetus communis, total flavonoids, orthogonal experiment, hydroxyl free radical, DPPH free radical