To improve the preparation method of acute myocardial ischemia reperfusion injury (MI/RI) model in rats, and to make comprehensive evaluation, to lay a good model foundation for the follow-up of MI/RI research.METHODS: 36 clean Wistar male rats were randomly divided into 3 groups: normal group , no intervention for left anterior descending coronary artery (LAD), sham operation group , only wearing line, no ligature of LAD, ischemia reperfusion group (MI/RI group), ligating LAD30min and reperfusion 120min. Rats after anesthesia and continuous ECG recording, tracheostomy ventilation, thoracotomy on rat LAD respectively after the intervention from the electrocardiogram, myocardial enzyme content, determination of infarct size and myocardial pathological examination and other aspects of the improved model for comprehensive evaluation.RESULTS: The electrocardiogram of group MI/RI showed obvious ST-T dynamic change. The level of CK-MB in group MI/RI was significantly higher than that in 2h , compared with Sham group, the infarct size of MI/RI group increased significantly, and the degeneration and necrosis of myocardial cells in MI/RI group were obvious, and inflammatory cells were extensively infiltrated. Conclusion the improved modeling method not only reduced the difficulty of operation, but also successfully established the rat MI/RI model, which laid a good foundation for further MI/RI research.