Thymoma is most often located in the middle of the anterior mediastinum, and on ct scan it appears as a classically rounded, and may be accompanied by lobulated soft tissue density shadows. Thymoma is the most common tumor in the anterior mediastinum. Generally, ct image can be diagnosed from both scanning and enhancement. 1. ct plain scan: morphologically, it is round, may be accompanied by lobulation, even cystic changes, hemorrhage, necrosis, and a few may be accompanied by punctate, rough or arcuate calcification. The density is soft tissue density, mostly located in the middle of the anterior mediastinum, a few occur in the posterior mediastinum or outside the mediastinum. Small thymoma is mostly located in one side of the midline, and large thymoma is mostly located in both sides of the midline. 2. ct enhancement: the solid part of the tumor can be seen to be strengthened uniformly, and the cystic part of the tumor can show low density and no enhancement. It is suggested that patients with thymoma should go to regular hospitals in time and listen to the opinions of professional doctors.