Objective: To investigate the effect of ischemic postconditioning on myocardial infarction and myocardial apoptosis in ischemia-reperfusion injury of rats, and the protective mechanisms thereof. Methods:Thirty-six healthy male Wistar rats(230-280 g) were randomly divided into three groups, ischemia-reperfusion group(Group I-R), ischemia 30 min and reperfusion 120 min without additional intervention; myocardial ischemic postconditioning group(Group Post), after 30 min ischemia, the rats were comprised 3 cycles of 10 seconds reperfusion followed by 10 seconds ischemia, and then the rats were reperfused 120 min; myocardial ischemic postconditioning+AG490(JAK2-STAT3 pathway inhibitor) group(Group Post+AG490), rats were treated with AG490 5 minutes before reperfusion, followed by myocardial ischemic postconditioning and 120 min reperfusion. The myocardial infarct size was measured by TTC staining. Apoptotic index of cardiomyocyte was detected by TUNEL. Results: Myocardial infarct size and myocardium apoptotic index were significantly reduced in Group Post compared to those in Group I-R(P ＜ 0.05). AG490 inhibited cardioprotective effect of ischemic postconditioning. Conclusion: Ischemic postconditioning provides potent cardioprotective effect. JAK2-STAT3 pathway mediates the cardioprotective effects of ischemic postconditioning.