Abstract: Struma ovarii is a rare disease in which the tumor is composed entirely of thyroid tissue, or thyroid tissue accounts for more than 50% of the total tumor. The author reported a case of a patient with struma ovarii with peritoneal metastasis who received medical treatment due to persistent abdominal distension. The characteristics of the case were analyzed according to the clinical manifestations, laboratory examination and imaging findings of the patient. Combined with relevant literatures, the imaging manifestations and causes of misdiagnosis of struma ovarii were further reviewed, so as to provide clinical basis for early diagnosis.