Abstract:A study has been made on the protective activities of active components extracted from Radix Astragali by using reactive oxygen species initiated lipid peroxidation of purified human erythrocyte membrane. The results show that the total flavonoids of Astragalus and total saponins of Astragalus can significantly inhibit the membrane lipid peroxidation generated by O2 , H2O2 and UV rays, while the total polysaccharide of Astragalus possesses weaker protective activity.