Abstract: Taking Moringa oleifera as the material, the polysaccharides were obtained by water extraction and alcohol precipitation.The acetylated Moringa oleifera polysaccharide derivatives were prepared by using acetic anhydride as acetylating agent. The technical conditions of acetylated modification were optimized with single factor experiment and orthogonal experiments, and the antioxidant activity was studied at the same time. The results indicated that the preparation optimal acetylated conditions for Moringa oleifera polysaccharides were as follows: reaction time 6 h, reaction temperature 60 ℃, acetylating reagent dosage 5 m L.The oxidation resistance research showed that the ability of removal hydroxyl free radicals and remove super oxide anion free radical ability were significantly enhanced.Acetylation could significantly improve the antioxidant activities of Moringa oleifera.