Children’s vitamin D supplementation in the following time is best: first of all, in the first 2 weeks after birth, the best supplementation, the purpose of vitamin D supplementation in this case is mainly to prevent the occurrence of vitamin D deficiency rickets. Because children’s breast milk or milk powder containing vitamin D content is not very high, it is easy to cause vitamin D deficiency, vitamin D deficiency in children is easy to cause vitamin D deficiency rickets. So in the child about 2 weeks after birth, you can routinely supplement vitamin D. Secondly, the best supplementation in children’s deficiency, mainly in children with vitamin D deficiency degree is more serious, children have serious symptoms, this time to give children a large dose of supplementation, is the therapeutic dose, to distinguish between the previous type of preventive dose.