Objective · To explore the risk factors for gestational diabetes mellitus (GDM) in Shenzhen. Methods · Four hundred and thirty-two GDM pregnant women and 409 pregnant women with normal glucose tolerance (NGT) who delivered from February 2014 to July 2015 in two hospitals in Shenzhen were enrolled. The data of pregnant women were collected. FBG and HbA1c in the first trimester and OGTT during 24-28 weeks’ gestation were tested. Logistic regression analysis was used to analyze the risk factors for GDM. Results · The age, pre-pregnant body weight and pre-pregnant BMI were higher in the GDM group than in the NGT group (P=0.000 for all). The differences in body weight and BMI before delivery between two groups were not statistically significant. The univariate Logistic regression analysis showed that there were statistical differences in GDM history, pre-pregnant overweight (BMI≥25 kg/m2), diabetes family history, and age≥35 years between two groups. The multivariate Logistic regression analysis indicated that GDM history, pre-pregnant overweight, diabetes family history, and age≥35 years were risk factors for GDM (P<0.05 for all). Conclusion · GDM history, pre-pregnant overweight, diabetes family history, and age≥35 years are the risk factors for GDM.