Abstract: Objective: To analyze the characteristics of ultrasound images of conjoined twins malformation in early pregnancy, and to improve the accuracy of ultrasound diagnosis of conjoined twin-fetuses. Methods: This is a retrospective analysis of 16 cases of conjoined twin-fetuses diagnosed by ultrasound in Northwest Women and Children′s Hospital and confirmed by follow-up. Two-dimensional ultrasound was used to observe the connection site, organ sharing and fusion degree of conjoined fetuses. Results: In 16 conjoined twins, there were 11 cases（68.75%） of parapagus dicephalus, 7 cases of thoracoperitoneal joint, 2 cases of thoracoperitoneal and sacrococcygeal joint, and 2 cases of only abdominal joint. In 4 cases（25.00%）of craniopagus，there were 2 cases of combined thoracoperitoneal joint，2 case of head joint；1 case（6.25%）of ischiopagus. Among all the cases, 5 cases were combined with other malformations, including 2 cases with neck hydrocyst tumor（1 case twins combined heart malformation）, 1 case with leafless whole forebrain, 1 case with upper limb radial absence, and 1 case with small jaw. Conclusions: For conjoined twin fetuses，diagnosis and termination of pregnancy should be done as soon as possible. Ultrasonography can directly show the position, common organs, degree of fusion and concomitant deformity of the conjoined fetus in the amniotic cavity，which is of great significance for judging the prognosis.

Key words: Ultrasonography, prenatal, Pregnancy trimester, first, Ultrasonography, Doppler, color, Prenatal diagnosis, Twins, conjoined