Recently, our center successfully completed a large diameter arterial catheter occlusion for a small low weight infant. The child was diagnosed with severe bronchopneumonia and unclosed ductus arteriosus after being found to have an unclosed ductus arteriosus since birth, and had recurrent bronchopneumonia since then. After 10 days of treatment, the pneumonia was basically healed, and the diameter of the arterial duct was measured by cardiac ultrasound at 3.5 mm. It was considered that the diameter of the duct was thick and the left-to-right shunt was large, which led to recurrent pulmonary infections and heart failure, and it was difficult to treat the child. However, the difficulty of the blocking surgery was also great and the risk was high. After repeated discussions with the anesthesiologists, the pediatric medical staff formulated a detailed treatment plan and successfully completed the blocking surgery for the child on June 10, after which the child recovered smoothly and was discharged on June 14. The child was 3 months and 20 days old at the time of surgery and weighed only 5 kg. The intraoperative angiogram showed a 4.2 mm diameter catheter with a large left-to-right shunt and hypoplastic descending aorta, which is by far the lowest weight, youngest age and largest diameter arterial catheter occlusion ever performed in our hospital.