This study was conducted to modify the method for establishing the model of myocardial infarction by ligation of the left anterior descending branch (LAD) of coronary artery in rats, and then observations on them were made with the use of electrocardiography, heart function exam and histomorphology. 30 adult male inbred strain Wistar rats were randomly divided into two groups: sham group (n = 5) and model group (n = 25). Each rat in the model group underwent a ligation of the left anterior descending branch. Subsequently, the two groups were compared by use of electrocardiography, heart function and histomorphology. The results have demonstrated that, after being improved, the ligation of the left anterior descending branch of coronary artery is a good method to establish the stable model of myocardial infarction. It can be applied to the research in mechanism and treatment of myocardial infarction.