Aim To make animal model of acute myocardial infarction in rats. Methods Rats were anesthetized by intraperitoneal injection of pentobarbital sodium solution,oral tracheal intubation under direct vision,the operating rats' ribcage,the left anterior descending coronary artery(LAD) was ligated.After the surgery,rat's respiratory tract was cleared.ECG,cardiac enzyme levels,pathological organization and measuring the infarct size were applied. Results 6 of 40 rats died during the surgery,the success rate was 85%.Thirty minutes after operation,Wistar rates'ECG showed the ST segment elevated and the pathological Q wave appeared;MB isoenzyme of creatine kinase(CK-MB),lactate dehydrogenase(LDH),LDH1 was compared in myocardial infarction group and sham-operation group before ligation of LAD.CK-MB,LDH,LDH1 in myocardial infarction group increased significantly than those in sham-operation group 24 h,40 h after occlusion(P><0.05).LDH and LDH1 also increased significantly at 60 h(P><0.05);Observing the histological section under the light microscope,it was found that pathological cardiac muscle cells were arranged in disorder,and cell uncleus pyknosis and chip occurred;ischemic myocardium weight / left ventricle wet weight was also significantly greater in myocardial infarction group than sham-operation group 40 h,60 h and 21 days after occlusion(P><0.01). Conclusion This showed that the technique was easy to operate with small wound high success rate and credibility.