OBJECTIVE : To investigate computed tomography (CT) features of exophthalmos in Chinese subjects with thyroid-associated ophthalmopathy (TAO). METHODS A total of 605 eyes of 325 patients with exophthalmos due to TAO were classified as grade I (mild exophthalmos) or II (severe exophthalmos) based on orbital CT imaging. The increased orbital volume features, such as changes from extraocular muscles, orbital fat, or both, were analyzed. RESULTS A total of 605 eyes were analyzed, among them 62.98% presented grade I exophthalmos, while 36.02% showed grade II exophthalmos. In grade I, 56.69% showed orbital fat change, and in grade II, 89.29% exhibited extraocular muscle enlargement. CONCLUSIONS Orbital fat and extraocular muscle enlargement are likely to be observed on CTs of subjects with mild and severe exophthalmos, respectively. Our results suggest that CT findings may guide TAO clinical therapy recommendations and prognosis.