Abstract: Objective: To investigate the protective effects of Ganoderma lucidum spore polysaccharide (GLSP) on liver injury caused by acetaminophen (APAP). Methods: Fifty mice were randomly divided into five groups: Blank group, model group, positive drug group, GLSP low-dose group and GLSP high-dose group, with 10 mice in each group. After each group was pre-administered according to the corresponding dose for 14 consecutive days, the liver index, serum indexes (glutamic oxalacetic transaminase (AST), glutamic-pyruvic transaminase (ALT)) and liver tissue plasma indexes (glutathione (GSH), malonaldehyde (MDA), superoxide dismutase (SOD), Caspase-3, Bax and Bcl-xl) were determined. Results: Compared with the blank group, ALT, AST, MDA and proapoptotic genes Caspase-3 and Bax were very significantly increased in the model group (P<0.01). The contents of SOD and GSH decreased very significantly (P<0.01), and HE staining showed that APAP treated mice showed typical lobular central necrosis of liver. Compared with model group, ALT and AST were very significantly decreased in polysaccharide dose group (P<0.01), SOD and GSH were significantly increased (P<0.05) and MDA was significantly decreased in polysaccharide low-dose group (P<0.05), SOD and GSH were very significantly increased (P<0.01) and MDA was very significantly decreased in polysaccharide high-dose group (P<0.01), and pro-apoptotic genes Caspase-3 and Bax were very significantly decreased in polysaccharide group (P<0.01), and the liver histopathological observation showed that the necrotic area of liver tissue decreased. Conclusion: Ganoderma lucidum spore polysaccharide can preprotect APAP liver injury, and its mechanism may be related to improving the antioxidant capacity of liver and inhibiting the occurrence of apoptosis.