The main symptom of coronary heart disease is chest tightness and chest pain, but many diseases can cause chest tightness and chest pain, so what tests should be done when chest tightness and chest pain occur? (1) Electrocardiogram. Electrocardiogram (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 easy to use and popularize. Whether it is angina pectoris or myocardial infarction, it has its typical electrocardiogram changes, especially for the diagnosis of arrhythmia has its clinical value. (2) Activity plate test: many patients with coronary artery disease, although the maximum reserve capacity of coronary artery dilatation has been reduced, usually the resting state of coronary artery blood flow can still be maintained normally, without myocardial ischemia manifestations, the electrocardiogram can be completely normal. To reveal reduced or relatively fixed blood flow, the presence of angina pectoris can be confirmed by exercise, which loads the heart and induces myocardial ischemia. (3) Ambulatory electrocardiogram: is a method that allows continuous recording and compilation and analysis of electrocardiographic changes of the heart in active and quiet states over a long period of time. The ECG can continuously record up to 100,000 ECG signals in 24 hours, which improves the detection rate of non-sustained ectopic rhythms, especially transient arrhythmias and transient myocardial ischemic episodes. (4) Coronary angiography: It is the “gold standard” for the diagnosis of coronary heart disease. It can clarify whether the coronary arteries are stenotic, the location, degree and extent of stenosis, etc., and can guide the measures to be taken for further treatment accordingly. (5) Cardiac ultrasound: cardiac ultrasound can examine the heart shape, wall motion and left ventricular function, which is one of the most commonly used means of examination at present. (6) Cardiac enzymology examination: it is one of the important means for the diagnosis and differential diagnosis of acute myocardial infarction. Clinically, the diagnosis of acute myocardial infarction can be clearly made on the basis of the sequence change of serum enzyme concentration and the elevation of specific isoenzymes and other positive enzymatic changes.