A 3-month-old female infant was brought to our hospital due to a heart murmur noted on a physical examination. The diagnosis of cor triatriatum sinister (obstruction), atrial septal defect (secundum), and pulmonary hypertension was made by transthoracic echocardiography, and surgery was proposed. In patients with obstructive cor triatriatum sinister, the return flow of blood from the pulmonary vein to the left heart was obstructed, which resulted in mild pulmonary hypertension (PH), and early surgery was required to relieve the obstruction. Physiologically, this condition is similar to mitral stenosis. The anesthetic strategies include avoiding tachycardia, ensuring myocardial contractility, maintaining blood volume, and avoiding hypotension. At the same time, it should also be noted to prevent an increase in pulmonary vascular resistance secondary to hypoxia and hypercapnia.