Abstract: To study the physicochemical properties and anti-tyrosinase activity of polysaccharide in Aegiceras corniculatum root, the crude polysaccharides were extracted from Aegiceras corniculatum roots by the sequential extraction methods of water extraction, acid extraction and alkaline extraction. The crude polysaccharides were depurated by degreasing, decoloration, deproteinization and dialysis, its physicochemical properties were examined by UV analysis and various chromogenic reactions, the effects on tyrosinase activity were also researched. The results were as follows: the polysaccharide (neutral polysaccharide) content of aqueous extract from Aegiceras corniculatum roots was 34.02%, acidic polysaccharose content of acid extract was 27.18% , and alkaline polysaccharide content of alkali extract was 51.21% . At the polysaccharose concentration of 0.2-1.0 mg/mL, it was found that the neutral polysaccharide and acidic polysaccharose had dual-directional regulation effects on tyrosinase activity, which showed the inhibition effect under 0.4 mg/mL and activation effect above 0.6 mg/mL, but acidic polysaccharose only showed activation effect.