Objective To analyze the causes of misdiagnosis of ovarian fibroma as subserous myoma before operation.Methods The clinical data of 10 patients with ovarian fibroma who were admitted from April 2019 to May 2021 and misdiag-nosed as subserous myoma before operation were retrospectively analyzed.Results The mass was detected in the upper left part of the uterus in all patients.There were 5 cases with lower abdominal pain and distension,3 cases with low back pain,2 cases with frequent and urgent urination,and 3 cases with irregular vaginal bleeding.Ultrasound examination showed a homog-enous mass of low echo in the upper left part of the uterus in all patients.A preliminary diagnosis of subserous myoma was made and surgical treatment was proposed.Ovarian fibroma was confirmed by the postoperative pathological examination com-bined with clinical diagnosis.The duration of misdiagnosis was 1-2 d.All 10 cases underwent total hysterectomy of double ad-nexa and were discharged after incision healing.Conclusion In patients without ascites,with pelvic masses,lower abdomi-nal distension,irregular vaginal bleeding,and tumor compression symptoms,and ultrasound examination can not identify the source of the tumor,it is more likely to be misdiagnosed as uterine fibroma before surgery.Strengthening the understanding of the disease,early vaginal color Doppler ultrasonography,and surgical pathological examination when necessary can effectively avoid or reduce misdiagnosis and mistreatment of ovarian fibroma.