Abstract: Objective To explore the relationship between the growth rate of body mass index and gestational diabetes mellitus.Methods Some variables were obtained by using questionnair e and antenatal care,and diagnosing gestat ional diabetes mellitus by using laboratory examination.Statistical analysis:relative risks and 95% confidence intervals were calculated by means of non-conditional Logistic regression.Results The risk for developing gestational diabetes mellitus was increasing with growth rate of pregnant body mass index(OR=89.1274,95%CI6.2574~95.1757),pre-pregnancy body mass index(OR=8.1826,95%CI7.1804~4.13126)years of ag e(OR=2.4322,95%CI2.2815~15.2251)and having family history of diabetes(OR=4.1254,95%CI4.0247~27.2024),but no statistical difference was observed in pre-pregnancy height.The faster women's growth rate of body mass index in duration of increase pregnancy,the more possible who would fall in ill with gestational diabetes mellitus.Conclusion The incidence of gestational diabetes mellitus was related to the growth rate of pregnant body mass index.