Objective To analyze the findings and diagnostic value of CT for primary thymic carcinoma. Methods The clinical data of 205 patients with thymic carcinomas who underwent CT examination in the hospital from March 2015 to March 2017 were analyzed retrospectively. Among them, 84 cases were confirmed by pathology as primary thymic carcinoma (thymus carcinoma group) and the other 121 cases were benign thymoma (benign group). CT findings of the two groups were compared, and the diagnostic value of CT for primary thymic carcinoma was analyzed based on pathological findings. Results CT findings of 84 patients with primary thymic carcinoma showed anterior upper mediastinal mass shadow, protruding to one side or bilateral pleural cavities, irregular shape or lobulation on edges, uneven density, cystic degeneration and necrosis, adjacent structure fat layer disappearing, invading surrounding tissue with distant metastasis. The ratios of tumor diameter and uneven enhancement, irregular shape, mediastinal fat layer disappearance, pericardial invasion, macro-vascular invasion, pericardial effusion and lymph node enlargement were higher in thymus carcinoma group than in benign group (P<0.05). The sensitivity, specificity, accuracy, positive predictive value, negative predictive value and kappa value of CT in diagnosing primary thymic carcinoma were 83.33%, 87.60%, 85.85%, 82.35%, 88.33% and 0.708, respectively. Conclusion CT findings of primary thymic carcinoma are typical. It can be identified with benign thymoma according to the size, shape, boundary and enhancement mode of tumors.