Objective To explore the value of combined use of high and low frequency ultrasound in the differential diagnosis of benign and malignant ovarian giant cystic masses.Methods The sonograms of 42 patients with ovarian giant cystic mass confirmed by surgery and pathology in our hospital from January 2018 to January 2020 were retrospectively analyzed. The maximum diameter of the mass was more than 115 mm, the minimum diameter was more than 90 mm, and the average diameter was more than 95 mm. The wall thickness, smoothness, papilla process, internal echo, internal blood flow signal and frequency spectrum were observed. The value of high and low frequency ultrasound in the differential diagnosis of ovarian giant cystic tumor were analyzed. Results Compared with the use of lowfrequency ultrasound alone,the combination of high and low frequency significantly improved the coincidence rate of benign and malignant diagnosis of giant ovarian cystic mass (94.44% vs 85.71%, P＜0.05).Conclusion The combined use of high and low frequency ultrasound had greater clinical value in the differential diagnosis of benign and malignant ovarian giant cystic masses.