Objective To investigate the CT features of primary thyroid lymphoma (PTL). Methods CT findings and clinical datas of 9 cases with PTL proved by pathology were retrospectively analyzed. Results There were 8 cases of diffuse large B-cell lymphoma, 1 case of mucosal-associated lymphoid tissue lymphoma, including 2 cases of solitary nodule type; 3 cases of multiple nodules type, 4 cases of diffuse swelling type. On CT scan , 7 cases showed slightly low density, 2 cases showed equal density, and 8 cases with uniform mass density, 1 case can be seen cystic necrosis at centerwithout calcification. Dynamic enhancement: 8 cases showed homogeneous mild enhancement, 1 case with cystic showed cyst wall annular significantly enhanced, solid areas showed heterogeneous moderately enhancement. 3 cases with thyroid encapsulated 6 cases with incomplete capsule and invased adjacent structures, 4 cases with lymph nodes at cervical or upper mediastinal. Conclusion PTL has certain CT features, mostly were diffuse swelling type, grew along thyroid contour shaping, mostly showed uniform density and enhanced of mild to moderate homogeneous, combined with biopsy to diagnose the disease.