The inhibiting effects of Chinonin, Quercetin and Tannic Acid on the lipid oxidation(LPO) induced by irradiation were investigated by means of a modifiedTBA spectrophotometry. The scavenging effects of these three active compounds onfree radicals were studied by ESR technique. The results showed that antioxidationeffects of Chinonin and Quercetin were better than that of Tannic Acid; thoughscavenging effects of the three active compounds were similar.