Objective：To observe the protective effect of Yulangsan polysaecharide（YLSPS） on diclofenac-induced liver injury in Kunming mice. Methods：The models of diclofenac-induced liver injury in mice with method of injection were used to study the pro－tective effect of YLSPS. Kunming mice were randomly divided into liver injured DICF group，NC group，YLSPS high-，middle-，low- group（600，300，150 mg/kg） and dimethyl diphenyl bicarboxylate（200 mg/kg DDB） group. The treatment groups were orally adminis－tered once per day whereas the normal and model groups were orally administered with saline for 14 d. Except normal group，all the other mice were injected intraperitoneally with DICF（50 mg/kg body weight）. After fasting for 20 h，animals were sacrificed and blood，liver samples were obtained. The levels of alanine aminotransferase（ALT），aspartate aminotransferase（AST），alkaline phos－phatase（ALP），total bilirubin（TBIL），tumor necrosis factor-α（TNF-α） and interleukin-1β（IL-1β） in serum and levels of superoxide dismutase（SOD），glutathione peroxidase（GSH-Px），catalase（CAT），malondialdehyde（MDA） in liver tissue were measured. Hema－toxylineosin（HE） stain was used to examine the degree of hepatic injury. Results：Compared with model group，YLSPS could reduce the levels of ALT，AST，ALP，TBIL，MDA，TNF-α and IL-1β. The activities of GSH-Px，SOD，and CAT could be increased （P<0.05），and the degree of hepatic injury could be lessened. Conclusion：YLSPS has protective effect on diclofenac-induced liver injury in mice. The mechanism may be related to attenuat－ing free radical and inhibiting the effect on lipid peroxidation.