Objective To understand the status quo of vitamin D deficiency in children,and to analyze the effects of vitamin D deficiency on serum ferritin. Methods Children aged 6 months to 14 years,who took physical examination in Dongguan Children′s Hospital from November 2016 to April 2018 were enrolled in this study.Serum ferritin and vitamin D concentrations of children were measured.Statistical analysis was performed by SPSS 24.0. Results The overall prevalence rate of vitamin D deficiency was 34.73%,and the prevalence rate of vitamin D deficiency in infants,preschoolers and school-age children was 19.75%,65.45% and 77.78%,respectively.The rate of iron depletion was 22.42%.The serum ferritin level in vitamin D normal group was higher than that in vitamin D depletion group and vitamin D deficiency group (F=6.21,P=0.002).Older age was a protective factor for iron depletion (OR=0.312,95%CI:0.233-0.419,P<0.001),and vitamin D deficiency was a risk factor for iron depletion (OR=1.377,95%CI:1.109-1.710,P=0.004). Conclusions The prevalence of vitamin D deficiency is still high in healthy children,and it increases with age.Vitamin D deficiency is one of the risk factors for decreased serum ferritin.Therefore,it is necessary to extend the duration of vitamin D supplements to reduce the prevalence of vitamin D deficiency in children.Besides,vitamin D concentration is suggested to be tested to rule out vitamin D deficiency for children with iron deficiency or poor efficacy of iron supplements