Catheterization is one of the necessary tools for the diagnosis of congenital heart disease. Although most congenital heart diseases can be correctly diagnosed without catheterization, complex congenital heart diseases must be diagnosed definitively by catheterization. This test involves putting a special catheter into different parts of the heart from an artery or vein, measuring the pressure, taking a blood sample, checking the blood oxygen concentration or injecting a contrast agent for X-ray imaging, and then analyzing the information obtained and the image of the contrast agent with blood flow to diagnose complex congenital heart disease. How is the correction of complex congenital heart disease in newborns performed? What type of procedure is adopted? The decision depends on the correct diagnosis. Therefore, preoperative diagnosis is very important, and catheterization can solve this problem. Through catheterization, not only the correct anatomical diagnosis can be made, but also the correct physiological diagnosis, which provides a very important guarantee for the design of the surgical approach. Catheterization is performed in different ways depending on the congenital heart disease, but there are two basic ways: one is to deliver a catheter from the femoral vein to the right atrium, ventricle or pulmonary vein; the other is to deliver a catheter from the femoral artery to the left atrium, ventricle or aorta. Cardiac catheterization is used for the following congenital heart diseases: 1. complex congenital heart disease requiring a thorough anatomical and physiological evaluation. 2. Congenital heart disease with left-to-right shunts with or without pulmonary hypertension requires knowledge of the pressure level and the exclusion of any other congenital heart disease. When congenital heart disease with right-to-left shunt has been combined with obvious pulmonary hypertension, postoperative pulmonary hypertension is not removed, and postoperative right ventricular drainage is obviously obstructed, producing low cardiac drainage and death due to untreatable right heart insufficiency. 3.Aortic arch lesion. 4.Postoperative evaluation of congenital heart disease. 5.Evaluation of vascular lesions. 6.Treatment of some congenital heart diseases through interventional catheterization, atrial septotomy and stoma to save some children with severe congenital heart diseases; balloon dilation, membrane plication, closure of atrial and ventricular septal defects and other interventional treatments. There are no absolute contraindications to cardiac catheterization. However, catheterization is contraindicated in the following cases: when the child has fever, sepsis, significant cardiac insufficiency, uncontrolled ventricular arrhythmias, uncorrected hypocalcemia, digitalis toxicity, and inadequate screening equipment. Although there are various methods of examining the heart, none of them can replace catheterization yet. Along with the development of modern medicine, catheterization is receiving more and more attention from the medical community, because catheterization can be used not only for the diagnosis of various congenital heart diseases, but also for therapeutic purposes, such as radiofrequency ablation of certain intractable arrhythmias via catheterization for the purpose of radical treatment.