Objective：To discuss the correlation between gestational weight gain and perinatal outcome in dichorionic twin pregnancies. Methods：Data of 350 dichorionic twin pregnant women meeting the inclusion criteria were retrospectively studied. Specifically they were divided into three groups according to the 2009 US Institute of Medicine US（IOM） recommendations of gestational weight gain（GWG），low GWG group with 145 cases（weight gain＜16.8 kg），recommended GWG group with 170 cases（16.8 kg ≤weight gain＜24.5 kg），and high GWG group with 35 cases（weight gain ≥24.5）. The data of pregnancy complication incidence and perinatal outcome were collected for correlation analysis by multiple logistic regression. Results：The morbidity of gestational hyper-tension was positively correlated with gestational weight gain（OR=1.087，95%CI=1.008 to 1.172，P=0.031）. The gestational ages at delivery were （35.29 ± 2.25） week in low GWG group，（36.32±1.33） week in recommended GWG group and （36.50±0.94） week in high GWG group respectively，and the differences were statistically significant（P＜0.001）. The multiple logistic regression suggested that the incidences of extreme preterm birth（OR=0.829，95%CI=0.749 to 0.918，P=0.000） and extreme premature rupture of membranes（OR=0.776，95%CI=0.688 to 0.874，P=0.000） were negatively correlated with gestational weight gain，and the differences were of statistical significance. Conclusion：In dichorionic twin pre-gnancies，gestational weight gain conforming to the recommendation of the IOM guideline was beneficial to reduce the incidence of pregnancy complications and to gain favorable perinatal outcomes.