The indications for coronary angiography are very wide. In developed countries, it is almost necessary for hospitalized patients with coronary artery disease to have the diagnostic information of coronary angiography, and some people say that as long as the operating physician’s title is qualified, the equipment is perfect, and the risk to the patient is within the acceptable range, all patients who need to show the coronary arteries to solve clinical problems have indications for coronary angiography. However, the scope of coronary angiography should not be expanded blindly without indications and without considering the timing and advantages and disadvantages of angiography. The indications for coronary angiography are broadly divided into two categories, the first category is unclear clinical diagnosis of coronary artery disease, mainly for diagnostic purposes, including the following; 1, unexplained chest pain, non-invasive tests can not confirm the diagnosis, clinical suspicion of coronary artery disease, the need for treatment according to coronary artery disease, such patients have a heavy mental burden, work and life stress, often around the medical expenses are also larger, and the chance of real coronary artery disease is not high. 2, unexplained arrhythmias, such as intractable ventricular arrhythmias and conduction block; sometimes coronary angiography is needed to exclude coronary artery disease; 3, unexplained left heart insufficiency, mainly seen in dilated cardiomyopathy or ischemic cardiomyopathy, the identification of the two often requires coronary angiography; 4, precordial disease and valvular disease Before surgery, age > 40 years, easily combined with malformations or atherosclerosis of the coronary arteries, which can be intervened at the same time as surgery; 5, asymptomatic but suspected coronary artery disease, in high-risk occupations such as pilots, car drivers, police officers, athletes, firefighters, etc. or medical insurance needs. The second major category is mainly for therapeutic purposes, the diagnosis of clinical coronary heart disease is clear, coronary angiography is performed to further clarify the scope of coronary lesions, the degree, to choose the treatment plan, mainly including the following: 1, stable angina, the effect of medical treatment is not good, affecting work and life; 2, unstable angina, the first to take medical active intensive treatment, once the condition is stable, active coronary artery angiography; internal drug treatment is ineffective or the symptoms do not relieve, generally need emergency imaging. For high-risk patients with unstable angina, spontaneous predominantly with obvious ECG S-T segment changes and post-infarction angina, coronary angiography can also be performed directly. 3, acute myocardial infarction, the main therapeutic measure for acute myocardial infarction is reperfusion therapy of occluded vessels, and PCI technology has been used as the preferred method for reperfusion therapy of acute myocardial infarction because of its high success rate and reliable effect. Hospitals that have the conditions should prefer direct coronary angiography for patients with acute myocardial infarction and perform PCI techniques, including balloon dilation and stenting of the coronary arteries. If PCI techniques are not available, for patients with contraindications to thrombolysis after AMI, such patients should be transferred to a hospital with conditions as far as possible. patients who have not recanalized with intravenous thrombolysis after AMI should seek remedial PCI measures in due course, and those who recanalize with intravenous thrombolysis should undergo coronary angina evaluation once post-infarction angina occurs. for patients without complications, coronary angiography should be considered about a week after infarction, elective Coronary angiography. AMI with cardiogenic shock, VSD, MI and other complications should be treated with early revascularization with the help of assisted circulation. For highly suspected AMI without confirming the diagnosis, especially with CLBBB, pulmonary infarction, aortic coarctation and pericarditis, coronary angiography can be performed directly to clarify the diagnosis. 4.Asymptomatic coronary artery disease, in which coronary angiography should be performed in patients with positive exercise test with obvious risk factors. 5.Primary cardiac arrest resuscitation is successful, and the possibility of left main stem lesion or proximal anterior descending branch lesion is high, which is a high-risk group and should be treated with early vascular lesion intervention, requiring coronary artery evaluation. 6. After bypass surgery or PTCA, angina recurs, and coronary artery lesion evaluation is often required again. There is generally no absolute contraindication to coronary angiography. If the current standardization of medical practice is considered, patients and their families do not agree that it is an absolute contraindication, mainly because coronary angiography still has the possibility of bringing complications to patients. However, the main clinical considerations are relative contraindications, including the following; 1, uncontrolled severe ventricular arrhythmias; 2, uncontrolled hypertension; 3, uncontrolled cardiac insufficiency 4, uncorrected hypokalemia, digitalis toxicity, electrolyte disorders; 5, febrile diseases; 6, bleeding disorders; 7, contrast allergy; 8, severe renal insufficiency; 9, acute myocarditis.