Abstract: Oyster polysaccharide was prepared from ostrea gigas thunberg by water extraction and alcohol precipitation. The hepatoprotective effect of oyster polysaccharide against alcohol-induced hepatic injury in mice was studied. The Kunming mice were oral administration daily with oyster polysaccharides at three doses of 80, 160, 320mg/kg respectively for 30 days. Then liver injury model was established by administration of 50 degrees intragastric ethanol in mice on the 30 th day. The positive control was administrated with 200mg/kg dimethyl diphenyl bicarboxylate. The activities of serum ALT, AST and ALDH, the content of MDA and the activity of SOD, ADH in hepatic tissue were measured. The hepatic histological changes were observed by optical microscope. The results showed that oyster polysaccharides had significantly hepatoprotective activity on alcohol induced liver damage in mice. The serum AST, ALT, ALDH and liver lipid peroxides in mice administrated with oyster polysaccharides decreased significantly compared with those of experiment control.The contents of MDA and ADH in hepatic tissue were also decreased while the activities of SOD increased significantly for the mice with oyster polysaccharides compared with those of experiment control. Histopathological changes induced by alcohol were also significantly reduced by oyster polysaccharides treatment. The results indicated that oysters polysaccharides had a protective role in acute alcoholic liver injury in mice.