Objective To investigate the effect of the mitochondria-targeted antioxidant SS-31 on acute liver injury in a mouse model of sepsis. Methods A total of 24 adult male C57BL/6J mice were randomly divided into control group, control+SS-31 group, lipopolysaccharide (LPS) group, and LPS+SS-31 group, with 6 mice in each group. The mice were given intraperitoneal injection of LPS (10 mg/kg) to establish a model of sepsis and acute liver injury, followed by intraperitoneal injection of SS-31 (10 mg/kg) for treatment, and the mice in the control group were given intraperitoneal injection of an equal volume of PBS solution, followed by intraperitoneal injection of an equal volume of normal saline. After 12 hours, ELISA was used to measure the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), reactive oxygen species (ROS), superoxide dismutase (SOD), tumor necrosis factor-α (TNFα), interleukin-1β(IL-1β), and interleukin-6 (IL-6), and HE staining was used to observe liver histopathological changes. A one-way analysis of variance was used for comparison of continuous data between multiple groups, and the least significant difference t -test was used for further comparison between two groups. Results Compared with the LPS group, the LPS+SS-31 group had significant reductions in the serum levels of ALT (140.05±12.22 U/L vs 102.64±8.75 U/L, P < 0.05) and AST (80.22±4.71 U/L vs 69.26±5.37 U/L, P < 0.05) and the levels of ROS (1 030.21±115.87 pg/mL vs 847.84±63.65 pg/mL, P < 0.05), TNFα (767.18±60.60 ng/mL vs 698.89±16.99 ng/mL, P < 0.05), IL-1β (29.97±1.37 ng/mL vs 26.70±3.09 ng/mL, P < 0.05), and IL-6 (59.13±7.09 pg/mL vs 49.29±3.41 pg/mL, P < 0.05) in liver tissue. Compared with the control group based on HE staining, the LPS group showed destruction of hepatic lobular structure, inflammatory cell infiltration, ambiguous intercellular space, and hepatocyte swelling, while the LPS+SS-31 group showed alleviation of inflammatory cell infiltration and hepatocyte swelling. Conclusion The mitochondria-targeted antioxidant SS-31 can reduce the production of ROS, downregulate the highly expressed inflammatory factors in sepsis, and alleviate sepsis-related acute liver injury in mice.