Objective To summarize the ultrasound characteristics of intramural pregnancy and evaluate the diagnostic value of vaginal three-dimensional ultrasound．Methods Intramural pregnancy was diagnosed by vaginal three-dimensional ultrasound and confirmed by surgery and pathological examination in 4 patients .The ultrasound characteristics of intramural pregnancy was summerized and analyze the reason of misdiagnose .Resuts Among the 4 cases, 3 of them were diagnosed correctly, 1 of them was misdiagnosed by vaginal ultrasound and be correctly diagnosed by vaginal three-dimensional ultrasound after 4 days later.Conlusion Vaginal three-dimensional ultrasound is of high value in the diagnosis of intramural pregnancy．