Abstract: Objective：To summarize the experience of surgical treatment of complex anterior mediastinum tumor and evaluate the efficacy of left innominate veinright atrial appendage bypass. Methods：The clinical data of 8 patients with anterior superior mediastinum tumor straddling the superior vena cava and left and right anterior veins were retrospectively analyzed. One patient had B2 and B3 mixed thymoma, 2 patients had B2 thymoma, 2 patients had mediastinal neuroendocrine cancer (carcinoid), and 3 patients had thymic squamous cell carcinoma. During the operation, left innominate veinright atrial appendage bypass with artificial blood vessels were performed, and the primary tumor and part of the superior vena cava involved were completely resected. Results：All 8 patients were discharged smoothly without serious complications during perioperative period, one patient died of bone metastasis 9 months after operation. Conclusions：Left innominate veinright atrial appendage bypass can improve resection rate, relieve clinical symptoms, and prolong survival of patients with mediastinal tumor that invade superior vena cava and left and right innominate veins without distant metastasis and causing superior vena cava syndrome.