We hereby report a rare case of a mature type teratoma that perforated the lung and combined with aspergilloma in the tumor cyst. The patient was a 48-year-old female, who complained of coughing and sputum. The chest roentogenography and chest CT suggested aspergilloma. The patient was operated upon. From the intraoperative and pathological findings, a mature type mediastinal teratoma was found to have perforated the bronchus and lung, and combined with aspergilloma in the cyst of the tumor. The tumor was resected, the drainage bronchus was closed. The mediastinal teratoma and aspergilloma have not recurred for two years and four months since the operation.