Pulmonary sequestration is a very rare congenital malfomation, especially when it is located in the infradiaphragmatic retroperitoneal space. The patient was a 56-year-old man with no respiratory symptom but had some postprandial epigastric discomfort for several days. Plain chest x-ray revealed mild elevation of left diaphragm and abdominal CT scan showed large cystic retroperitoneal mass with some calcification. We performed the operation through the thorachoabdominal incision and the mass was proven to be a pulmonary sequestration. Therefore, we report the case with review of literatures.