With the aim of studying the change in the difference before and after the ST segment on the ECG interference corresponding lesion of the coronary artery branches in patients with acute myocardial infarction, research was performed on 300 patients with myocardial infarction coronary intervention percutaneous. Results as follows: In the hospitalized group in the first 24 hours, ST reduces real difference in patients who have lesions before ventricular branch artery (LAD) I in V3, V4, V5 and V1 to V5 in LAD II after intervention 24 hours. In the hospitalized group after 24 hours, ST reduces real difference in patients with lesions in LAD I V1, V2, V4, for LAD II in V1 to V4 intervention after 24 hours. For the right coronary artery lesions: ST decreased immediately post-ihtervention and after 24 hours in both LAD I, LAD II in. 011, Dill, aVF.