Objective:To investigate the effects of different processing products of Cortex Phellodendri on scavenging oxygen free radicals and anti-lipidperoxidation. Method:The oxygen free radicals generation system and mouse liver homogenate lipid peroxidation in vitro were used. Result:The aqueous and 80% alcohol extracts of raw,stir-fried,stir-fried with salt,stir-fried with yellow alcohol products of Cortex Phellodendri could scavenge superoxide radical(O2*)generated through hypoxanthine-oxidase system and(*OH)generated through Fenton action,and inhibit lipid peroxidation induced by hydroxyl radical generation system,respectively.But the carbonized product has no effect.There are differences among these processed products.Conclusion:80% alcohol extract of stir-fried with yellow alcohol products of Cortex Phellodendri was more intense.