Coronary angiography is now widely used in the diagnosis and treatment of coronary artery disease. With the growth of coronary interventionalists, the improvement of teamwork, the accumulation of operational experience, and the updating of relevant instruments and equipment, the complications and risks associated with coronary angiography and intervention are very low. However, it cannot be denied that coronary angiography and intervention is still an invasive procedure and there is still a small probability of complications in a large population sample (but probably not as high as the probability of traffic accidents) that patients and families need to be aware of. Among these small complications, those that are relatively common include: 1. Allergic reaction to contrast media: mainly occurs in patients with allergies or known allergies to iodine-containing foods or contrast media. Allergic reactions such as rash and chills can occur, but severe allergic reactions such as shock are extremely rare. The catheterization room is routinely equipped with anti-allergy drugs such as epinephrine and dexamethasone as well as other rescue drugs, which can be detected and handled in time. 2. Infection: Some patients may develop fever after surgery and consider intervention-related transient bacteremia. For patients without immunodeficiency or severe immune deficiency, the fever can usually subside on its own or improve with the application of antibiotics, and can generally be cured. Arrhythmias: Changes in coronary blood flow during cardiography, especially during interventional procedures, can cause transient arrhythmias, such as premature ventricular beats or even ventricular tachycardia or ventricular fibrillation, to occur in a small percentage of patients. Even if they occur, the patient’s blood pressure and heart rhythm will be closely monitored intraoperatively, and most of them can be detected and treated in time. 4, bleeding: because patients apply diphtheria antiplatelet drugs before surgery, intraoperative use of heparin (part of the simple coronary angiography without heparin), will make the body’s internal environment is not conducive to hemostasis, there may be the occurrence of bleeding. Other internal bleeding, including cerebral hemorrhage and gastrointestinal bleeding, can be life-threatening. As with other complications, the chance of hemorrhage is very low, but its occurrence is relatively insidious, so the risk of hemorrhage will be fully evaluated before surgery, blood pressure and heart rate will be closely monitored during and after surgery, and blood count will be reviewed after surgery to be alert to the occurrence of this complication. 5, puncture local hematoma: now generally take the radial artery way in, another part of patients take the femoral artery way in. Postoperative radial artery or femoral artery local hematoma may appear, but most can be self-absorbed; a very small proportion of patients, mainly in severe peripheral arteriosclerosis, diabetes, elderly, local pseudoaneurysm or arteriovenous fistula may appear, need to re-pressure bandage under ultrasound localization, or surgical patch treatment. 6, contrast nephropathy: intraoperative contrast agent needs to be metabolized by the kidneys, for the elderly and diabetic patients, the risk of contrast nephropathy is higher than other patients, preoperative and postoperative will be fully assessed kidney function, preoperative and postoperative will be fully hydrated, alert to the occurrence of contrast nephropathy. 7, myocardial infarction, shock, acute left heart failure, cardiac rupture, aortic coarctation: these possible complications are even more of a small probability among small probabilities, the chance of occurrence is extremely low, mostly seen in critically ill patients. Cardiac angiography is a technically mature test, and most centers are experienced in the management of complications. However, patients and families should be fully informed about its complications and risks and assess the benefit and risk ratio.