The congenital heart diseases that can be complicated by pulmonary hypertension are congenital heart diseases with left-to-right shunt, such as atrial septal defect, ventricular septal defect, patent ductus arteriosus, complete atrial septal defect, ectopic drainage of pulmonary veins, and double outlet of right ventricle. The mechanism of occurrence is mainly left-to-right shunting of intracardiac blood resulting in increased pulmonary blood volume and elevated pulmonary artery pressure. If the left-to-right shunt can be interrupted, the pulmonary artery pressure will return to normal. If the pulmonary artery pressure continues to rise, the pulmonary artery endothelium and middle layer will become hyperplastic, the lumen will narrow, the blood flow will be slow, and microembolism will form, further aggravating the pulmonary hypertension, and the pulmonary artery itself will become diseased at this time, even if the left-to-right shunt is interrupted, the pulmonary artery pressure will not decrease. When the pulmonary artery pressure rises above the left ventricular pressure, a right-to-left shunt occurs, and because venous blood is mixed with arterial blood, the patient then develops cardiogenic cyanosis, followed by right heart failure and death. At this point, clinically known as Eisenmenger syndrome, the patient has cyanosis, pestle-like fingers (toes), hepatomegaly, ascites, and bilateral lower extremity edema. Pulmonary hypertension is usually classified as mild, moderate or severe according to the pressure. Pulmonary artery pressure of 30-60 mmHg is mild, 60-90 mmHg is moderate and over 90 mmHg is severe. The timing of surgical treatment for pulmonary hypertension is very important. Generally, surgical treatment for pulmonary hypertension below moderate level has a better healing, while above moderate level has poor results and is risky. We usually encounter several cases of Eisenmenger’s syndrome developing in late stages every year, mostly in the age of 20, and the parents and the child are traumatized. Generally, in the early stage of pulmonary hypertension in precordial disease, the child’s diet and activities are not affected, and parents think that the problem is not serious, but by the time symptoms appear, a good time for surgery may have been lost. Therefore, it is recommended that once a child is found to be suffering from precardiac disease, he or she must go to a regular hospital for examination and diagnosis in a timely manner, and listen to the treatment advice of professionals to obtain the best time for surgery. It is recommended that patients with such diseases can be treated surgically at the age of 1-3 years if the symptoms are not obvious, or as early as possible within the age of 1 year if there is recurrent pneumonia, heart failure, upper sensation and malnutrition. For mild to moderate pulmonary hypertension, preoperative application of prostaglandin, longtopril, sildenafil and other pulmonary artery pressure-lowering treatment for 1-2 weeks can be performed surgically, while for patients with severe pulmonary hypertension, preoperative oxygenation, cardiac and diuretic therapy, as well as the application of pulmonary artery pressure-lowering treatment for 4-6 weeks after the review of pulmonary artery pressure, and measurement of whole lung vascular resistance, such as whole lung If the total pulmonary vascular resistance is greater than 8wood units, surgery is contraindicated, and greater than 4wood units is a high-risk patient with high surgical risk and poor prognosis. IV. Prognostic effect For mild to moderate pulmonary hypertension the postoperative recovery is better, the pulmonary vasculature can generally recover to normal human standards after surgery, while severe patients can not immediately recover from the small pulmonary arteries after surgery, some patients will gradually recover after surgery, while a small number of patients may continue to aggravate pulmonary vascular disease, resulting in right heart failure, so severe patients should continue to will continue to treat pulmonary artery pressure after surgery. In view of the above, it is strongly recommended that patients with congenital heart disease should go to the hospital as early as possible for examination and diagnosis to assess the degree of disease development, and it should be pointed out that there are early, middle and late stages of congenital heart disease like tumors, so do not make the mistake of thinking that the child can eat and drink, run and jump, and develop to late stages without treatment, losing the time for surgical treatment, ruining the child’s life, and bringing great regret and guilt to doctors and parents.