Common primary mediastinal tumors are: ① neurogenic tumors: many originated from sympathetic nerve, and a few originated from peripheral nerve; Most of them are located in the posterior mediastinum; ② Teratoma or dermoid cyst: mostly located in the anterior mediastinum, in front of the great cardiac vessels near the bottom of the heart; ③ Thymoma: mostly located in the anterior superior mediastinum, divided into three types: epithelial cell type, lymphocyte type and mixed type; ④ Mediastinal cysts: such as bronchial, pericardial and esophageal cysts; ⑤ Intrathoracic ectopic tissue tumors: For example, retrosternal goiter is mostly located in the anterior upper mediastinum; Lymphoid tumors are mostly located in the middle mediastinum; ⑥ Other rare tumors: such as hemangioma and lipoma.