Objective:This study tried to analyse the ultrasonographic features of ectopic hydatidiform moles. Methods: This was a retrospective study to analyze 9 cases with ectopic vesicular block confirmed by pathologic diagnosis from January 2012 to December 2018. The clinical characters, ultrasound files, treatment and pathological diagnosis were reviewed.Results:The mean age of 9 patients was 37.3 years. The initial clinical symptoms were menopause, abnormal vaginal bleeding and abdominal pain. All patients preformed surgerical treatment. One of them developed into gestational trophoblastic neoplasia. Ultrasound images showed that the location was in fallopian tube (4/9), anterior isthmic scar (3/9) and uterine horn (2/9), which were totally consistent with the situation in the operation. The sonographic appearance of the lesion was snow-strom sign (6/9), embryo sac-like heterogeneous echo with or without follicular sac and germ (3/9), which was similar to intrauterine hydatidiform mole. Conclusion: Transvaginal ultrasound is able to decide the EMP location, but need to be confirmed by pathological diagnosis. Close follow-up for EMP is required due to the potential character of developing to gestational trophoblastic neoplasia.