Defatted soy meals were extracted with ethanol aqueous solution to soybean saponins and the extract was analyzed qualitatively by means of thin-layer chromatography,infraed spectroscopy and high performance liquid chromatography.Meanwhile,its protecting effects against the lipid oxidation in bean oil were investigated.The major components in the defatted soy meals were soybean saponins.The extract could effectively protect bean oil from lipid oxidation in a dose-dependent manner and presented higher protecting effect at the dosage of 0.5%,which,however,corresponded with that of 0.02% BHT.Synergistic protecting effects between ascorbic acid or citric acid.Soybean saponins from defatted soy meals are a potential natural antioxidant.