By analysis of child mortality rate under age 5 in Jiangsu Province from 2005 to 2016, we aimed to forecast child mortality rate under age 5 from 2017 to 2020 in order to provide references for maternal and child health care. The gray model GM （1,1） was established by Matlab software to predict the child mortality rate under age 5 in Jiangsu Province. The established prediction model was [x（1）（t+1）=-121.349e-0.062 8t]+129.909, and the predictive accuracy of the model established was at a high level: C=0.103 7, P=1. The model precision was good. The predicted child mortality rate under age 5 for 2017 to 2020 was 3.70 ‰, 3.48 ‰, 3.26 ‰, 3.07 ‰, respectively. GM （1,1） can predict the child mortality rate under age 5, and the child mortality rate under age 5 in Jiangsu Province will decline continuously. At the same time, more attention should be paid to the health of children, so as to keep the child mortality rate under age 5 at a lower level.