Objective: To explore the influence of pre-pregnancy body mass index (pBMI) and gestational weight gain (GWG) on maternal outcomes in twin pregnancies. Methods: Clinical data of women with twin pregnancies delivered in Women’s Hospital School of Medicine Zhejiang University from January 2014 to December 2014 were collected and retrospectively analyzed. The women were classified into three groups according to pre-pregnancy body mass index based on WHO guidelines, and gestational weight gain based on the Institute of Medicine (IOM) classification. The characteristics, blood glucose, serum lipid and obstetrical outcomes were compared among the groups of women. Results: Three hundred and twelve eligible women with twin pregnancies were identified. Fifty-nine of the women were underweight, 226 had a normal weight, and 27 were overweight or obese. Fasting blood glucose, OGTT-1H, glycosylated hemoglobin, triglycerides in second and third trimester in overweight or obese group were significantly higher when compared with the normal weight group. Overweight or obese increased the risk of hypertension (OR2.86; 95% CI, 1.15-7.13) and intrahepatic cholestasis (OR, 4.01; 95% CI, 1.51-10.84) compared with normal weight. GWG among women with twin pregnancies was low (n = 125), moderate (n = 143) or high (n = 43) based on pBMI. High GWG increased the risk of preterm birth (< 32weeks gestation) (OR, 5.49; 95% CI 1.47-20.44) while low GWG increased the risk of low birth weight (< 2500 g) (OR, 1.95; 95% CI, 1.20-3.19).Multivariate linear analysis showed gestational weeks, GWG and gestational hypertension had effects on birth weight (P < 0.05). Conclusion: Pre-pregnancy overweight or obese in women with twin pregnancies adversely influence glucose levels, serum lipid concentrations and perinatal outcomes. Preterm and birth weight are adversely influenced by excessive or insufficient GWG.