Abstract:Objective To explore the clinical characteristics, diagnosis, treatment and prognosis of malignant struma ovarii （MSO）, and improve the level of clinical diagnosis and treatment. Methods Combined with one case of MSO diagnosed and treated in Department of Obstetrics and Gynecology of General Hospital of Eastern Theater Command, the literature was reviewed and the experience was summarized. Results MSO is an ovarian goiter whose histological diagnostic criteria are consistent with primary thyroid cancer or biological behavior with distant invasion and metastasis. Due to clinical rarity, there is still a lack of clear diagnostic criteria and treatment principles. It is considered that surgery is the first choice of treatment. Patients with complete early tumors can have surgery to remove the affected side of the appendix. Staged surgery should be performed for tumor rupture or extra-ovarian metastasis, and adjuvant treatment should be performed after surgery. Conclusion MSO is rare, and surgical treatment is the preferred method. The type of operation should depend on the patient’s age, fertility requirements and tumor conditions. Patients with metastasis should be treated with adjuvant therapy after operation. Long term follow-up is needed after operation.