Objective To establish the model of myocardial infarction by ligation of the left anterior descending branch in rats.Method Adult inbred strain Wistar rats were randomly divided into sham group(n=6) and model groups(n=79).Model of myocardial infarction were established by ligation of the left anterior descending branch.The electrocardiogram(ECG),HE staining tissue sections,and heart function of the rats were compared in the two groups.Results Rats in the model group had showed special changes of ST-T and Q wave in ECG,show serious necrosis of myocytes and proliferation of fibrous tissue compared with rats in the sham group.The left ventricular systolic pressure(LVSP),left ventricular develop pressure(LVDP),?dp/dt_(max),heart rate(HR) were significantly decreased in the rats of model group than those of the sham group(P