Objective This study evaluated whether liver ischemic preconditioning has delayed protective effect on liver ischemia-reperfusion injury and probe into the protective mechanism.Methods 36 wistar rats were randomly divided into two groups, group A:ischemic preconditioning,Group B:Control. The group A rats were subjected to liver ischemic preconditioning,While group B rats were subjected only laparotomy.After 48 hours,Liver tissue samples were abstained to detect the expression of HSP70.Occlusion the inflow vessels to the left and median lobes 45-minute then reperfuse 90-minute.Liver tissue samples were abstained to detect the expression of TNF-?.Serum ALT was detected before ischemia and after 90-minute reperfusion.Results The serum ALT level in group A is much lower than that in group B (P