The present work was designed to investigate the antioxidant and hepatoprotective effects of acidic-hydrolysis Lentinus edodes residue polysaccharides (Ac-LRP) on lipopolysaccharide-induced liver injury in mice. Hepatoprotective effects were observed in liver treated with Ac-LRP at doses of 200, 400, and 600 mg/kg body weight, respectively. Activities of superoxide dismutase, glutathione peroxide, catalase, total antioxidant capacity, alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase and levels of total cholesterol, triglyceride, malondialdehyde, and lipid peroxidation in liver or serum samples were analyzed. Ac-LRP reduced the incidence of liver necrosis detected via histological observations. In addition, Ac-LRP chemical bonds and ultrastructure were measured. These results provided valuable evidence supporting the utilization of Ac-LRP as a functional food and natural medicine for the treatment of liver injury.