Abstract: Objective To investigate the affect of intervention of diet and exercise on pregnancy outcome in the first trimester of those with high risk of gestational diabetes mellitus(GDM) in community. Method From August 2017 to August 2018, 438 pregnant women who had established Beijing maternal and child health manual in qingyundian town were randomly divided into the intervention group and control group. In intervention group, 215 cases were given individualized guidances of diet and exercise intervention on early stage.223 cases in control group were treated with routine management during pregnancy. Follow up the occurrence of complications during pregnancy and the outcome of delivery in the two groups. After the delivery, the complete pregnancy and the delivery of the medical record could not be considered as a case-out, and in the end,183 cases of the intervention group and 185 cases of the control group were obtained. The incidence of GDM, gestational hypertension, polyhydramnios, oligohydramnios, preterm birth, cesarean section, macrosomia, low birth weight infant, fetal distress and postpartum hemorrhage were compared between the two groups. Result The incidence of GDM, gestational hypertension, fetal distress, cesarean section and postpartum hemorrhage in intervention group was lower than that in control group,the difference were statistically significant(P< 0. 05). There was no significant difference in the incidence of polyhydramnios, oligohydramnios, preterm birth, macrosomia and low birth weight infant between the two groups(P>0. 05). Conclusion Carry out dietary and exercise intervention in first trimester by community health service centers can effectively reduce the incidence of GDM in high-risk groups and reduce the incidence of some related obstetric complications.