OBJECTIVE: To analyze the sonographic features of different histopathological subtypes of borderline ovarian tumors (BOTs) confirmed by pathology, and to study the ultrasound performances of various types in borderline ovarian tumors. STUDY DESIGN: Retrospective analysis was performed on the pathological results and ultrasound projection findings of 129 patients diagnosed as BOTs by ultrasound department of our hospital from January 2012 to November 2019. All patients were confirmed by surgical pathology and scanned consecutively by the investigators using transabdominal or transvaginal ultrasound examination. RESULTS: Serous borderline tumors (SBOTs) were observed, and the prevalence rate (53%) was significantly higher than that of other subtypes, and the probability of bilateral lesions was higher (40%). The sonogram often showed ultrasound features of papillary neoplasm in the lesion and good internal echo (p<0.05). Mucinous borderline ovarian tumors (MBOTs) were mostly unilateral lesions (86%). The prevalence was second only to SBOTs. Histomorphological examinations were divided into gastrointestinal-type and endocervical-type. Among them, the gastrointestinal type of MBOTs were mostly unilateral, and their incidence was higher than that of endocervical-type of MBOTs. Compared with other pathological subtypes, the gastrointestinal type is more likely to show the sonographic characteristics of huge space occupying in the pelvic and abdominal cavity (mean diameter > 10 cm), polycystic, multiple septums, and poor internal echo (p<0.05). The ultrasonographic features of the endocervical-type of MBOTs were simi-lar to those of SBOTs. Compared with gastrointestinal type, the sonographic images showed smaller lesion diameter, less septal or cyst, and more papillary excrescences in the tumor (p<0.05). The borderline clear cell tumor is the intermediate transition between the clear cell adenofibroma and the clear cell carcinoma. The clinical manifestations are diverse and lack specificity. The histology of sonography was mainly solid, and the multiple microcapsules were honeycomb-like. It can also be shown as cystic. Among the 169 patients with BOTs, 20 cases of SBOTs, 17 cases of MBOTs, and 10 cases of other rare subtypes were complicated with other diseases or multiple subtypes. This study did not find significant ultrasonic characteristics were used for distinguish them from other subtypes. CONCLUSION: BOTs is a common disease in women during the reproductive period. It is characterized by the development of malignant tumors. Its clinical and pathological subtypes are complex and diverse. It leads many doctors to use the terms "large pelvic mass" and "solid ovarian mass" for diagnosis because of their lack of experience and understanding.