Abstract: Objective To investigate the nutritional status of vitamin D among children and adolescents in Yinchuan and Wuzhong city of Ningxia,and to provide a scientific reference for the prevention of Vitamin D insufficiency and deficiency among children and adolescents.Methods Stratified cluster samphng method was used to extract classes from the randomly-selected primary,middle and high schools of Yinchuan and Wuzhong city.The patients of rickets,Crohn's disease,cardiovascular disease,liver and kidney disease,and the children and adolescents with Vitamin D supplements history in the last 3 months were excluded.2 167 children and adolescents aged from 7 to 18 were selected as subjects.The fasting venous blood was collected and the concentration of serum 25(OH) D was determined by enzyme-linked immunosorbent assay(ELISA).Results The serum 25 (OH) D concentration among 2 167 children and adolescents was 51.46nmol/L,the interquartile distance was 61.46 nmol/L,the sufficient,insufficient and deficient detection rates of vitamin D were 51.9%,14.1% and 34.0%,respectively.The detection rate of insufficiency was at the highest at 7 years old,and then showed an upward tendecny during 8-13 years old with increasing of age,while started to decrease gradually at the age of 14.The deficiency detection rates of children aged 7-18 years were 31.9%,27.9%,20.8%,30.1%,36.7%,42.4%,29.8%,32.3%,35.3%,47.5%,37.3% and 32.8%,respectively.The differences of Vitamin D levels and deficiency detection rates among different age groups were of statistical significance (H =43.086,P< 0.01,x2 =11.156,P =0.001).The differences between Hui and Han children were of no statistical significance for the level of Vitamin D and insufficient and deficiency detection rates.Conclusion The children and adolescents aged 7-18 years in Yinchuan and Wuzhong are found of high detection rate of vitamin D deficiency.With the increase of age,the levels of Vitamin D among children and adolescents decreased,the deficiency detection rate increased significantly.