Abstract: Objective To investigate the clinical features， pathological features， and diagnosis of primary ovarian leiomyosarcoma. Methods The diagnosis and treatment of 1 patient with primary ovarian leiomyosarcoma admitted were retrospectively analyzed，and relevant literature was reviewed. Results The 77-year-old patient showed symptoms of abdominal pain and a pelvic mass，and an imaging examination found a large pelvic mass of about 20 cm. The patient received primary debulking surgery. The postoperative diagnosis was ovarian leiomyosarcoma. The postoperative survival has been 10 months. Conclusion Primary ovarian leiomyosarcoma is a rare and highly invasive tumor with atypical clinical symptoms. The diagnosis is based on histopathology，and the prognosis is poor.

Key words: primary ovarian leiomyosarcoma, clinical manifestations, pathology, diagnosis