In 1987, an extensive multicenter investigation was done in the United States, and further understanding of the epidemiology and etiology of primary pulmonary hypertension was achieved. Diagnosis and treatment have also improved from the past, but the prognosis of the disease is still poor, with most deaths occurring within a few years after the onset of symptoms. Although Romberg first reported a case of unexplained pulmonary hypertension in 1891. However, it was not until 1950 that “primary pulmonary hypertension” was diagnosed after the introduction of cardiac catheterization. Primary pulmonary hypertension (PPH), a rare occlusive disease of unknown origin involving moderate and small pulmonary arteries, causes right ventricular failure or fatal syncope 2 to 5 years after detection. The prevalence is 1:5 in men and women, mostly in women of childbearing age. The average age at diagnosis is 35 years, and the younger the patient, the worse the prognosis. Almost all cases have endothelial hyperplasia and the narrowing of the vascular lumen that it causes. More advanced cases have multiple mid-layer hypertrophy and hyperplasia. Irreversible plexiform damage and necrotizing arteritis (reticulopathy) are present. The same clinical course of vascular damage is seen in some cirrhosis and in some patients taking the appetite suppressant drug dexfenflu-ramine-phentermine (fen-phen) in combination, which is no longer available in the United States. Progressive exertional dyspnea is present in more than 95% of cases, and precordial pain on exertion and syncope are rare. Many patients have Raynaud’s phenomenon and arthralgia, which usually appear several years before the onset of significant primary pulmonary hypertension. The prognosis for patients with primary pulmonary hypertension 30 years ago was disastrous, with an average survival of only 2 to 3 years after the onset of symptoms. Recently, acute trials of vasodilator drugs and long-term treatment have found remission or cessation of progression in about 20% of patients, improving the prognosis to some extent; the success of single-lung transplantation has led to a marked improvement in long-term survival for organ transplantation, all of which give hope for the treatment of patients with primary pulmonary hypertension. Continuous fetal circulation is often serious, and in addition to heart failure, left heart failure is also manifested in severely ill children, and the morbidity and mortality rate is even as high as 50% Some children have a tendency to remit spontaneously, while some others continue to deteriorate after treatment, with significant hypoxia and finally causing acidosis death. However, in general, the results of drug treatment are satisfactory in most children, and the duration of the disease is about a few days to half a month after treatment.