Ischemia and hypoxia of the myocardium lead to the development of angina pectoris. The most important cause of angina pectoris is coronary artery lesion, other include aortic valve lesion, hypertrophic cardiomyopathy, pulmonary hypertension and some other systemic disease factors. 1, coronary atherosclerosis: In patients with angina pectoris, coronary artery lesion itself, especially coronary atherosclerosis is the main pathological cause, accounting for 80-90% of patients with angina pectoris. Atherosclerosis and narrowing of the coronary arteries occur, resulting in insufficient blood supply to the heart. 2, other pathological factors affecting coronary circulation: such as coronary artery spasm, microcirculatory disorders, etc. can cause vascular stenosis, resulting in insufficient blood supply to the heart, thus triggering angina pectoris. Such as nighttime vagus nerve tension, resulting in vascular spasm, triggering variant angina. Weather changes or violent mood swings, etc. often trigger the onset of angina on the basis of the original coronary artery lesion. 3, aortic valve lesion: high aortic valve stenosis or incomplete closure can cause myocardial ischemia, is the most important cause of angina other than coronary artery lesions. If such patients are combined with coronary artery disease, angina can occur in cases where the coronary stenosis is not severe. 4, hypertrophic cardiomyopathy: myocardial hypertrophy when the capillaries within the myocardium do not match the hypertrophied myocardial fibers, resulting in a relative lack of blood supply to the hypertrophied myocardium, which is clinically manifested as atypical chest pain. 5, pulmonary hypertension: all diseases that can cause pulmonary hypertension caused by pulmonary heart disease will have atypical chest pain symptoms, mainly due to right ventricular hypertrophy, increased myocardial oxygen demand, and lead to a lack of relative blood supply. 6, other diseases: such as anemia, hyperthyroidism, pheochromocytoma, severe hypertension, etc. can induce myocardial ischemia and occur angina pectoris. Diabetes causes diffuse stenosis of microvessels causing microvascular angina. Angina is the result of the conflict between blood and oxygen demand and blood and oxygen supply, leading to myocardial ischemia and hypoxia. There are many causes of angina pectoris, but coronary atherosclerosis is a common clinical cause, and patients need to improve the relevant examination to clarify the cause.