With the rapid development of modern technology and the in-depth research and exploration of medical researchers on coronary heart disease, the methods of diagnosing coronary heart disease have been improved day by day. In the early days, people mainly diagnosed coronary heart disease myocardial infarction and coronary artery insufficiency based on typical clinical manifestations (including symptoms and signs), myocardial enzymatic examination and electrocardiographic features. In recent years, many new examination methods and techniques have been developed, such as radionuclide examination, echocardiography, coronary angiography, cardiac blood pool imaging, etc. used in the diagnosis of coronary heart disease. 1.Clinical manifestations: mainly include symptoms and signs. Angina pectoris is the main clinical symptom of coronary artery disease, and it is possible to distinguish angina pectoris from myocardial infarction according to the characteristics of angina pectoris such as location, nature, trigger, duration and relief mode, and the accompanying symptoms and signs. 2, ECG: ECG is the earliest, most commonly used and most basic diagnostic method in the diagnosis of coronary heart disease. Compared with other diagnostic methods, ECG is convenient to use and easy to popularize. When the patient’s condition changes, the changes can be captured in time, and continuous dynamic observation and various load tests can be performed to improve its diagnostic sensitivity. Whether angina pectoris or myocardial infarction, there are typical ECG changes, especially for the diagnosis of arrhythmia has its clinical value, but of course there are also certain limitations. 3, ECG load test: mainly includes exercise load test and drug test (such as pansentine, isoproterenol test, etc.). Electrocardiogram is the most common simple method for clinical observation of myocardial ischemia. When angina attacks, ECG can record the abnormal ECG manifestations of myocardial ischemia. However, in many patients with coronary artery disease, despite the fact that the maximum reserve capacity of coronary artery dilation has decreased, coronary blood flow can usually remain normal at rest without myocardial ischemic manifestations, and the ECG can be completely normal. To reveal reduced or relatively fixed blood flow, the presence of angina can be confirmed by exercising or other methods that load the heart and induce myocardial ischemia. Exercise tests are also essential for the evaluation of cardiac function after ischemic arrhythmias and myocardial infarction. 4.Electrocardiogram: It is a method that can continuously record and compile and analyze changes in the ECG of the heart in active and quiet states for a long time. This technique was first used by Holter in 1947 to monitor electrical activity, so it is also called Holter monitoring. The conventional ECG can only record waveforms of a few tens of cardiac cycles at rest, while the ECG can record up to 100,000 ECG signals continuously within 24 hours, which increases the detection rate of non-sustained ectopic rhythms, especially transient arrhythmias and transient episodes of myocardial ischemia. The time of appearance can correspond to the patient’s activity and symptoms. 5.Nuclear myocardial imaging: According to the medical history, this test can be done when angina cannot be ruled out by ECG examination. Nuclear myocardial imaging can show the ischemic area and clarify the location and extent of ischemia. Combining with exercise test and re-imaging, the detection rate can be improved. 6.Coronary angiography: It is the “gold standard” of coronary artery disease diagnosis. It can clarify the presence or absence of coronary artery stenosis, the location, degree and extent of stenosis, and can guide the measures to be taken for further treatment. At the same time, left ventriculography can be performed to evaluate cardiac function. The main indications for coronary angiography are: (1) for those with severe angina despite drug treatment, to clarify the arterial lesion in order to consider coronary stenting; (2) for those with chest pain that resembles angina but cannot be diagnosed. 7, ultrasound and intravascular ultrasound: cardiac ultrasound can examine the morphology of the heart, ventricular wall motion and left ventricular function, and is currently one of the most commonly used examination methods. It has important diagnostic value for ventricular wall tumor, intra-cardiac thrombus, heart rupture, and papillary muscle function. Intravascular ultrasound can clarify the wall morphology and the degree of stenosis within the coronary arteries, which is a promising new technology. 8. Myocardial enzymatic examination: It is one of the important means for the diagnosis and differential diagnosis of acute myocardial infarction. The diagnosis of acute myocardial infarction can be clearly made clinically based on the sequence changes of serum enzyme concentration and the elevation of specific isoenzymes and other affirmative enzymatic changes. 9.Cardiac blood pool imaging: It can be used to observe the dynamic images of ventricular wall systole and diastole, which has important reference value for determining ventricular wall motion and cardiac function.