【Abstract】Objective To study the mechanisms of enhancing effect of mild hypothermia (MH) to ischemic preconditioning (IP) on hepatic ischemiareperfusion (I-R) injury. Methods To observe the content of the marker enzymes of liver damage (ALT,AST,LDH) and malondialdehyde (MDA), and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPX), total antioxidase (TAX) in inferior vena cava blood above liver in nonischemic control group (n=6), I-R group (n=6), IP group (n=6) and mild hypothermic ischemic preconditioning (MHIP) group (n=6). Results After I-R the content of ALT,AST, LDH and MDA were significantly elevated (P＜0.01), SOD,CAT,GSH-PX,ACT activities were declined obviously (P＜0.01). The content of ALT,AST,LDH and MDA were significantly lower in IP group than those in I-R group, and in MHIP group than those in IP group (P＜0.01,P＜0.05), and the content of SOD, CAT,GSH-PX, ACT activities were significantly higher in IP group than those in I-R group, and in MHIP group than those in IP group (P＜0.01,P＜0.05). Conclusion Ischemic preconditioning may enhance the oxidation-resistance of liver, and reduce the oxygen free radical injury to liver after ischemia-reperfusion. Mild hypothermia may enhance the protective effect of IP on hepatic ischemiareperfusion injury.