Unstable angina is a common type in clinical practice, and its ECG performance is as follows: 1. Conventional ECG: It mainly shows S-segment depression or elevation, T-wave inversion or biphasic, and there is a dynamic evolution between its changes and the ECG changes in the absence of an attack, so, it is also called dynamically evolving ST-T segment changes, and its ECG performance can return to normal as angina relieves or disappears. If the ST-T segment changes persist for more than 6 hours, a transmural myocardial infarction needs to be considered to have occurred. In addition, it should be noted that some of the unstable angina, its ECG can be without any change; 2, dynamic ECG: that is, continuous detection of abnormal ECG for 24 hours, most patients have asymptomatic myocardial ischemic ECG changes, 80%-95% of dynamic ECG changes are not accompanied by symptoms of angina pectoris. For the prognosis of unstable angina, ambulatory ECG is more sensitive than conventional ECG. It is not only helpful to detect dynamic changes in myocardial ischemia, but also can be used as a reference indicator for the evaluation of conventional anti-anginal drug therapy and decision on the need for coronary angiography and revascularization in patients with unstable angina; 3. Exercise ECG: It is suitable for patients whose symptoms have stabilized or disappeared, and is often used to determine the prognosis of unstable angina. Patients with normal resting ECG and negative exercise test, with or without chest pain, can have exercise plate ECG, which is helpful for timely detection of unstable angina.