Atrial septal defect of 4 cm cannot be interventional surgery. Interventional surgery is generally suitable for patients with atrial septal defects between 4mm and 3cm in size. Atrial septal defects of 4cm are large and require surgical treatment. The surgical treatment is to cut the right atrium after establishing extracorporeal circulation and use patch material directly for repairing treatment. If there is a partial ectopic pulmonary vein connection, a patch should be used to isolate the ectopic pulmonary vein opening into the left atrium. Primary foramen ovale-type atrial septal defects should be repaired before repairing the atrial septal defect with a patch. Atrial septal defect 4 cm patients are not timely treatment, the condition will gradually develop, may appear exertional dyspnea, arrhythmia, heart failure, etc., the late stage of about 15% of the patients due to severe pulmonary arterial hypertension appear right to left shunt with cyanosis, the formation of Eisenmenger syndrome, when the patient loses the opportunity for surgery, the treatment will be very tricky. Therefore, atrial defect 4 cm patients should go to the hospital in a timely manner, improve the examination to rule out contraindications, with the help of the doctor for surgical treatment, to avoid further development of the condition.