Background: Partial urorectal septum malformation sequence is a rare congenital malformation of urorectal septum dysplasia and failure of the breakdown of th cloacal membrane, is characterised by abnormalities of the ambiguous genitalia, urogenital organs, a single perineal/anal opening that drains a common Cloaca, and absent anus. We report a case of partial urorectal septum malformation sequence, who was suspected on pregnancy ultrasound scan at 24+6 weeks' gestation in our department and confirmed upon delivery. Case presentation: A 19-year-old married woman, Gravida 1 Para 0, presented to antenatal clinic of Cheng Du Women and Children's Central Hospital, Si Chuan province, China, at 24+6 weeks' gestation by dates, when ultrasound examination was performed, showing a very small common cloaca in the lower abdomen, absence of bladder, ambiguous genitalia and imperforate anus. Both mother and clinicians agreed on termination of pregnancy. The mother spontaneously delivered a dead female fetus weighing 1085 grams at 25+4 weeks' gestation after amniotic cavity injection rivanol, who had multiple congenital anomalies including imperforate anus, smooth perineum, absence of normal urethral and vaginal openings, absent bladder, uterus, vagina, and urethra, in combination with a very small common cloaca opening in the perinea and myelomeningocele in the sacral vertebrae. Conclusion: The characteristic features of the URSMS in ultrasonography are relate to the type of the URSMS, not all URSMS along with very dilated cystic regions in the abdomen.