Objective To investigate the findings and diagnostic value of CT in pulmonary metastasis of differentiated thyroid carcinoma. Methods The clinical data of 121 patients with DTC were retrospectively analyzed. All were confirmed by CT guided biopsy or surgical pathology and underwent chest CT examination. The sensitivity, specificity and accuracy of CT examination in the diagnosis of DTC with pulmonary metastasis were recorded and analyzed and the CT findings of patients with pulmonary metastasis were observed. Results Among the 121 cases of DTC patients, 9 cases were diagnosed with pulmonary metastasis by biopsy or surgical pathology, accounting for 7.4%; 6 cases with pulmonary metastasis and 100 cases of non-pulmonary metastasis were correctly diagnosed by CT. The sensitivity, specificity and accuracy of chest CT for DTC with pulmonary metastasis were 66.7% (6/9), 89.3% (100/112) and 87.6% (106/121), respectively; 6 patients with pulmonary metastasis diagnosed by CT showed that the diameter of the lesions was >3mm, including 3 cases with lesions of 3-5mm and 3 cases larger than 5mm; The images showed multiple different sizes of circular, miliary nodules or masses. The nodules density was homogeneous and the boundaries were clear, most of them distributed in the bilateral lung and outside the inferior field. Conclusion Chest CT examination can be used as an effective method for the clinical assistant diagnosis and treatment of DTC with pulmonary metastasis and provide basis for the successful development of the follow-up treatment.