Objective To explore the preventive effects of comprehensive nursing intervention on gestational diabetes mellitus in high-risk pregnant women.Methods It was a randomized controlled trial. High-risk pregnant women were randomly divided into the experimental group and the control group. In addition to nursing care in the control group,the experimental group received comprehensive nursing intervention,including：the establishment of WeChat public account for health education and answering questions,monitoring and guidance of weight,regular follow-up,guidance from a nutritionist. The control group received routine obstetric care. All subjects received pregnancy care manual,participated the course of “nutrition and weight management during pregnancy” at least once,and received a questionnaire about lifestyle and diet. The subjects were followed up until delivery. The blood glucose of 75 g oral glucose tolerance test（75 g OGTT）,BMI before pregnancy,weight at delivery,occurrence of gestational diabetes mellitus,and pregnancy outcomes were recorded.Results The incidence of gestational diabetes in the experimental group was 19.9%,it was 33.6% for the control group,and the difference was significant（P<0.05）. The weight gain of the experimental group was lower than the control group,and the difference was statistically significant（P<0.05）;the incidence of macrosomia in the experimental group was significantly lower than that in the control group（P<0.05）. There was no significant difference in the rate of cesarean section and premature delivery between two groups（P>0.05）.Conclusion Comprehensive nursing intervention in early pregnancy can effectively reduce the incidence of GDM in high risk population,reduce weight gain during pregnancy,and reduce the incidence of macrosomia.