Abstract: Objective:To investigate the scavenging effects of seabuckthorn polysaccharides on free radicals and anti-lipid peroxidation in vitro. Methods:The scavenging ability of seabuckthorn polysaccharides to DPPH free radicals,hydroxyl radicals·(OH)and superoxide anion(O₂^-·)and the total reducing ability of seabuckthorn polysaccharides were determined by in vitro antioxidant activity method. Sulphur,model of spontaneous lipid peroxidation of mouse liver homogenate in vitro,model of lipid peroxidation induced by CCl₄ in mouse liver homogenate,H₂O₂ in vitro induction of lipid peroxidation model of mouse liver homogenate,induction of lipid peroxidation in mouse liver by Fe²⁺-V_C in vitro,and the inhibition effect of seabuckthorn polysaccharide on lipid peroxidation was observed by TBA chromogenic method. Results:Hippophae rhamnoides polysaccharides had certain scavenging ability to DPPH free radicals,·OH free radicals and O₂^-·free radicals,and their IC₅₀ values were 1.55,1.23 and 8.31 mg/mL,respectively. At a concentration of 2 mg/mL,the reducing power was slightly higher than the same concentration of V_C. Seabuckthorn polysaccharide inhibited spontaneous lipid peroxidation and liver lipid peroxidation induced by CCl₄,H₂O₂ and Fe²⁺-V_C in mouse liver homogenate,and its IC₅₀ values were 1.10,1.59,9.13,1.39 mg/mL.Conclusion:Hippophae rhamnoides polysaccharide has certain antioxidant activity and anti-lipid peroxidation.