Abstract: Objective : To study the antioxidant activity of Lycium ruthenicum ( polysaccharide, flavonoids and polyphenols) extracts, as well as protective effect on mitochondrial. Methods:Polysaccharides, flavonoids and polyphenols were extracted from Lycium ruthenicum Murr. Comparison of their antioxidant activity was carried out by scavenging of DPPH radical, hydroxyl free radical (·OH) and superoxide anion radical (O2-·) . The inhibit effects of Lycium ruthenicum extracts on liver mitochondria swelling and malondialdehyde (MDA) content were measured. Results :Lycium ruthenicum contains abundant polysaccharide, flavonoids and polyphenols, the contents of polysaccharide, flavonoids and polyphenols were 30.6mg/g, 21.3mg/g and 49.5mg/g of dry Lycium ruthenicum, respectively. The free radical scavenging capacity of flavonoids and polyphenols from Lycium ruthenicum were stronger than that of polysaccharides. The free radical scavenging capacity of polysaccharides, flavonoids and polyphenols were 52.5%, 72.4% and 82.3% against DPPH free radicals, ·OH 48.2%, 56.6% and75.8% against ·OH, 16.1%, 40.7% and 53.3% against O2-·, respectively. Flavonoids (p<0.01) and polyphenols (p<0.01) from Lycium ruthenicum were significantly inhibit mitochondria swelling caused by Fe SO4 and VC, and flavonoids and polyphenols can significantly reduce the mitochondrial MDA content ( p <0.05) . Conclusion :Extracts from Lycium ruthenicum (polysaccharides, flavonoids and polyphenols) had antioxidant activity and mitochondrial protection, flavonoids and polyphenols protection stronger than the polysaccharides of mitochondria.