Objective To study the MRI characteristics of Ovarian thecoma in order to improve diagnostic value. Methods In this retrospective study, preoperative MRI examinations of 12 women with pathologically proven Ovarian thecoma were reviewed. and their clinical datas were collected. MRI features, including the location, shape, size, outline of Ovarian thecoma, visibility of bilateral ovaries, T1 and T2 signal and Timesignal intensity curve of were recorded and collected. Results All solid adnexal masses appeared oval, lobulated or bilobed, and well defined in all cases. Most Ovarian thecomas were isointense to hypointense compared with myometrium on T1-weighted images and isointense to hyperintense compared with myometrium on T2-weighted images. Capsule was noted in 6 of 12 cases.and central degeneration was present in 5 Ovarian thecomas, and peripheral degeneration was seen in 1 case. All the lessions had heterogeneous enhancement pattern, we found that the enhancement of Ovarian thecomas was significantly lower than that for myometrium at all time points. In addition, ascites and pleural effusion was involves in all women. Conclusion Ovarian thecomas were all defined solid masses, sometimes associated with degenerative changes. Time-signal intensity curve of MRI has been reported to aid in this distinction. Enhancement of Ovarian thecomas was significantly less than that for myometrium at all time points.