Objective：To analyze the characteristics of CT and MRI of struma ovarii. Methods：The imaging characteristics of 8 patients with pathologically proved struma ovarii were analyzed retrospectively. Results：Two cases were located in the left accessory and 6 cases were in the right. Plain CT and contrast CT were performed on 5 cases. All of the cases were cystic and solid；calcification was found in 2 cases. The solid component，cyst wall，interval of all cases were significantly enhanced；the cystic fluid showed no en－hancement. Plain MRI and contrast MRI were performed on 3 cases；all were cystic and solid. The solid components were intermediate intensity on both T2-weighted images and T1-weighted images. The signal intensity of different cysts was various. The areas of promi－nent low intensity on T2-weighted images were recognized in 2 cases，which were intermediate or high intensity on T1-weighted images. The solid component，cyst wall，interval of all cases were significantly enhanced；cystic fluid showed no enhancement. Conclusion：The prominent low intensity on T2-weighted images on MRI and the high density cyst’ on CT are the characteristic ex－pressions of struma ovarii.