Mitral stenosis can arise from a variety of causes, but the most common cause is rheumatic fever, which accounts for more than 90% of mitral stenosis causes. Mitral stenosis is an obstructive abnormality at the level of the left ventricular inflow tract membrane due to structural pathological changes in the left ventricular diastolic filling phase. The normal mitral valve is composed of a continuous funnel-shaped leaflet between the left atrium and the left ventricle separated by the anterior and posterior junction (actually two tangents). The mitral valve is connected to the junction and edge of the valve by a fan-shaped tendon from two groups of papillary muscles in the left ventricle. The normal mitral valve orifice area is about 4-6 cm2, and the orifice area is less than 2.5 cm2 to cause the corresponding clinical performance. Generally, the orifice area is less than 2 cm2 for moderate stenosis and less than 1 cm2 for severe stenosis. Mitral valve lesions in rheumatic heart disease are mainly manifested in diffuse fibrous thickening of the valve leaflets and edges, accompanied by varying degrees of calcified deposits, leaflet junction adhesions, thickening of the tendon cords, shortening and fusion, resulting in limited mitral valve body activity and reduced orifice area. The process of mitral stenosis in rheumatic heart disease is a slow and gradual change, usually involving the junctional and subvalvular structures of the valve first, followed by the free edge of the valve, the posterior leaflet body, and the anterior leaflet body in a sequential pathology pattern; severe pathological changes in the anterior leaflet body are mostly seen in severe mitral stenosis. Mitral stenosis prevents left atrial blood flow from entering the left ventricle during diastole, compensatory enlargement and hypertrophy of the left atrium, volume overload of the left atrium, and increased pressure in the left atrium produce a trans-micronodular pressure differential step. The magnitude of the trans-micronomic pressure difference reflects the level of left atrial pressure and the degree of mitral stenosis. The transvalvular pressure difference generated by increased left atrial pressure can overcome the resistance of mitral stenosis to maintain diastolic left ventricular filling and meet the beat volume; transvalvular blood flow is proportional to the square of the transvalvular pressure difference; in patients with mitral stenosis, doubling the beat volume requires a fourfold increase in the transvalvular pressure difference. When the pulmonary capillary pressure is higher than 30 mmHg, the plasma is extravasated and can be drained by the lymphatic vessels initially, but when the body is exercising or in a tachycardic state, because the right heart and pulmonary artery return flow increases, the pressure in the pulmonary capillaries increases sharply, the plasma is extravasated sharply, and the lymphatic system drains the plasma. Inadequate lymphatic drainage will result in acute pulmonary edema. Cardiac-induced pulmonary vascular changes include decreased pulmonary compliance, decreased ventilation to blood flow ratio, and decreased oxygen content in pulmonary veins, resulting in pulmonary artery constriction and pulmonary hypertension. Long-term pulmonary hypertension causes thickening of the intima and middle vessel walls of the pulmonary arteries and narrowing of the vessel lumen, which exacerbates pulmonary hypertension and leads to increased right ventricular afterload, right ventricular dilation and hypertrophy, and eventually right heart failure. Treatment of mitral stenosis clinically includes medical medication, cardiology catheter intervention, and cardiac surgery. Before choosing a treatment method, it is important to understand the advantages and disadvantages of various treatment methods in order to correctly select the appropriate treatment method and treatment timing according to the patient’s condition. The fundamental problem of mitral stenosis is the mechanical obstruction of blood flow at the level of the mitral valve during the diastolic filling phase of the heart due to the valve lesions produced by rheumatic heart disease. In patients with mild mitral stenosis without clinical symptoms and sinus rhythm, the left ventricle is only in a low-volume, low-load protected state because of mitral stenosis, so there is usually no clinical significance of drug therapy; considering the rheumatic etiology of mitral stenosis, antirheumatic therapy is necessary as appropriate. For mitral stenosis of moderate degree or above, when there is an increase in the volume load of the body circulation and the shortening of the diastolic filling period of the left ventricle due to the acceleration of the heart rate, etc., resulting in elevated left atrial pressure and an increase in the transvalvular pressure difference leading to obvious clinical symptoms, the symptoms can be relieved by limiting salt intake, intermittent diuresis, and the application of β-blockers or calcium channel blockers to slow down the heart rate; when accompanied by left or right heart insufficiency, digoxin can be taken Cardiac stimulant therapy. In addition, patients with atrial fibrillation should be treated with anticoagulation and medications to remove or control atrial arrhythmias as appropriate. The timing of mitral balloon dilatation and surgery: After understanding the pathologic features of rheumatic mitral stenosis and the role of various therapeutic approaches, the correct diagnosis of the patient’s condition is the basis for the correct choice of treatment and timing. The diagnosis of rheumatic mitral stenosis and the corresponding differential diagnosis are established with the help of medical history, physical examination, chest Х-ray, electrocardiogram and echocardiogram. Pulmonary artery pressure and trans-micuspid orifice pressure for combined coronary ischemic heart disease Renal function, liver function, neurological function, coagulation status, any special conditions (e.g., pregnancy, advanced age, etc.) These points can help us to identify individual differences in the patient’s condition, especially the presence of certain high-risk factors, in order to determine the correct treatment and timing. With the help of the ACC/AHA guidelines for the treatment of valvular disease, the catheter interventional and surgical procedures for rheumatic mitral stenosis are summarized in a chart for reference, with descriptions added as appropriate based on our clinical experience.