Objective To investigate the rate of vitamin D supplementation and related factors in children under 3 years old. Method A total of 600 children who received planned immunity and health care in child care clinic the Third Affiliated Hospital of Zhengzhou University were randomly selected in this study from January 2016 to December 2016. Self-made questionnaires were used to investigate the application of vitamin D and were filled out by main caregivers. Results The rate of vitamin D supplements for infants in Zhengzhou was 63.5%. Vitamin D supplements were started at 3 months old on average,and were stopped at 15 months old. Multi-factor Logistic regression analysis suggested that age (OR=0.816,95%CI=0.586~0.912),maternal education level (OR=0.573,95%CI=0.319~0.881) and feeding patterns (OR=0.346,95%CI=0.272~0.874) were the factors affecting the application of vitamin D supplements. Conclusions Vitamin D supplements in infants are unreasonable,and health education should be prompted in order to guide children use vitamin D supplements appropriately.