Abstract: Objective：To analyze the perinatal outcome of monochorionic diamniotic twins (MCDA), so as to explore the prognosis of perinatal fetus and provide a theoretical basis for prenatal counseling and clinical management. Methods：A retrospective study was conducted on 299 cases of MCDA. According to the complications, the cases were divided into non-complication group, twin-twin transfusion syndrome (TTTS) group, selective intrauterine growth restriction(sIUGR) group, and twin anemia-polycythemia sequence (TAPS) group. The perinatal outcome was compared among four groups. Results：In TTTS and TAPS group, the gestational age at delivery was significantly less compared with that in non-complication group. In three complication groups, the average birth weight of little fetuses was significantly less compared with that in non-complication group (P<0.05), moreover, for birth weight difference of the twin, the incidence of ＞25% was also significantly higher (P<0.01). The incidence of perinatal death in TTTS group (8.8%) and sIUGR group (3%) was significantly higher than that in non-complication group (1.5%, P<0.05). The incidence of congenital malformations was high in MCDA, among which, deformities in cardiovascular system, skeletal systemand urinary system were on the top three. The incidence of congenital malformations in TTTS group was significantly higher than that in non-complication group and sIUGR group (P<0.05). Conclusions：MCDA complicated with TTTS or sIUGR has poor perinatal outcome. For those pregnant women with MCDA complications, the regular prenatal examination is required to be strengthened for improving the fetal prognosis.