Objective To improve the preparation method of rat model of acute myocardial ischemia reperfusion injury(MI/ RI), to make a comprehensive evaluation and to lay a good model foundation for following MI/ RI research. Methods Thirty?six clean grade Wistar rats were randomly divided into 3 groups: normal group without intervention of the left anterior descending coronary artery (LAD), sham operation group with only wearing thread but no ligation of the coronary artery, and ischemia reperfusion group, with ligation of the LAD for 30 min and reperfusion for 120 min. Rats after anesthesia had continuous ECG recording, and tracheostomy for mechanical auxiliary ventilation. Thoracotomy and LAD intervention were carried out on the rats, and then the rat models were comprehensively evaluated by electrocardiography, detection of myocardial enzyme content, determination of the infarct size, and pathological examination of the myocardium. Results The electrocardiogram of the MI/ RI group showed obvious ST?T dynamic changes. The level of CK?MB in the MI/ RI group was significantly increased at 2 h after surgery. Compared with the sham group, the infarct size of the MI/ RI group was significantly increased, with evident degeneration and necrosis of cardiomyocytes and extensive inflammatory cell infiltration in the myocardium. Conclusions The improved modeling method not only reduced the difficulties of operation, but has also successfully established the rat model of MI/ RI, providing a good foundation for further MI/ RI research.