Abstract: Objective To analyze the influencing factors of serum 25-hydroxyvitamin D 25-(OH) D level in primary school children in Zhengzhou,and to provide the basis for prevention of metabolic bone disease in children.Methods A total of 3587 primary school children from Zhengzhou who underwent physical examination in the hospital from August 2016 to September 2017 were enrolled as study objects. The general data were collected. The content of serum 25-(OH) D was detected by enzyme linked immunosorbent assay (ELISA). The Pearson test was used to analyze correlation between children's age and serum 25-(OH) D content. The multiple Logistic regression analysis was used to analyze the risk factors of vitamin D deficiency in children.Results Among 3587 children,there were 2474 boys and 1113 girls,The age and the average age of the children were 7-13 years old and (9. 56 ± 0. 39) years old,respectively. According to serum 25-(OH) D content detection by ELISA,it was found that in 3587 children,the incidence of vitamin D deficiency was 7. 58%. The content of serum 25-(OH) D in first grade children was higher than that in the other grades children (P< 0. 05). Pearson test showed that serum 25-(OH) D content was positively correlated with age (r = 0. 591,P< 0. 05). The multiple Logistic regression analysis showed that outdoor activity time shorter than 3 h/d,poor appetite and irregular taking cod-liver oil were risk factors of vitamin D deficiency in children (P< 0. 05).Conclusion The results of this study suggest that the time of children's outdoor activities can be increased and cod-liver oil is regularly taken to prevent the occurrence of vitamin D deficiency. Therefore,in order to reduce the incidence of vitamin D deficiency,the children should be encouraged to participate more in the outdoor exercise and to popularize the relevant knowledge,and to improve the importance of their families to take the cod-liver oil and the regular diet