After myocardial infarction occurs, myocardium will undergo the process of damage and necrosis, and with the course of time the electrocardiogram will undergo the characteristic changes such as ST-segment upward sloping, bow-back elevation, T-wave inversion, and so on. In the hyperacute stage, there will be a tall T wave on the ECG, and the ST segment will be upward sloping or bow-back up elevated. In the acute phase, the bow-back elevation of the ST segment may show a significant unidirectional curve followed by a gradual decrease. Myocardial necrosis leads to a gradual decrease or even disappearance of the R-wave amplitude and reappearance of abnormal Q-waves.The T-wave changes from upright to inverted and necrotic Q-waves may appear. In the subacute phase, the elevated ST segment gradually returns to baseline, but due to ischemia, the T wave may gradually become shallow from inversion, when necrotic Q waves persist. In the healing stage, the ST segment and T wave gradually return to normal, the T wave remains inverted or low, and the residual necrotic Q wave still exists. In case of myocardial infarction, it is recommended to consult a doctor in time to clarify the cause with the help of the doctor and carry out targeted treatment or therapy.