UPVA (Unilateral pulmonary vein atresia) is the failure of connection between the common pulmonary vein and the left atrium. UPVA is a rare malformation of common pulmonary vein caused by embryonic development defects. Isolated UPVA is uncommon, the diagnosis commonly occurs during early childhood because of asthma, recurrent pneumonia or hemoptysis, but diagnosis in adults is unusual. Some patients can be asymptomatic until adulthood. In this report, we describe a case about UPVA presenting with recurrent hydrothorax in an adult. We gradually carried out routine diagnostic methods and eventually confirmed the rare UPVA according to the two common clinical manifestations of repeated pleural effusion and hilar soft tissue shadow.