Abstract: Objective:Studying the antioxidant activity of Schisandra chinensis polysaccharides in vitro and its protective effect on mitochondrial membrane potential of macrophages induced by lipopolysaccharide(LPS). Methods:Schisandra chinensis polysaccharides was extracted by hot water extraction method and four-factor three-level orthogonal analysis method L₉(3⁴). Compared the antioxidant activity of Schisandra chinensis polysaccharides with vitamin E polyethylene glycol succinate(V_E-TPGS)in vitro. The model of macrophage induced injury by LPS to study the inhibitory effect of Schisandra chinensis polypeptide on ROS and the protective effect on cell mitochondrial membrane potential by reactive oxygen species(ROS)and JC-1 cell staining. Results:The extraction process of polysaccharide from Schisandra chinensis was material-liquid ratio 1:40 g/mL,the extraction times 3 times,the extraction time 3.0 h,the extraction temperature 90 ℃. Under this condition,the highest yield was 10.72%. The total sugar contents of Schisandra chinensis polysaccharide was 84.28%±2.03%,the glucose contents was 30.26%±1.12%,and the IC₅₀value of DPPH free radical scavenged was 602.52 μg/mL,hydroxyl radical scavenged was 34.24 μg/mL by Schisandra chinensis polysaccharide. When the Schisandra chinensis polysaccharide was 1600 μg/mL,the total antioxidant capacity reaches 0.28±0.01 mmol/mg. Cell experiments showed that Schisandra chinensis polysaccharide could reduce the level of reactive oxygen species and inhibit the decreasing of mitochondrial membrane potential after LPS induced macrophages. Conclusion:The Schisandra chinensis polysaccharide had strong antioxidant activity in vitro,and would inhibit LPS-induced reactive oxygen levels and exert its protective effect on mitochondrial membrane potential in macrophages.