For infants of different sizes, the interval between breastfeeding and formula feeding is different, as explained below: First, for infants aged 3-6 months, the interval between breastfeeding and formula feeding is generally 3-6 hours. Because in this period of time that can be fully absorbed breast milk, can also be ready for the absorption of milk powder, and because the baby’s age is relatively small, so the absorption function is poor, the interval should be longer. Second, for infants aged 6-9 months, the interval between breast milk and formula is 2-4 hours, because as the infant grows, the infant’s absorption function will increase, so the interval between feeding breast milk and formula should not be too long. Because the interval is long, it may lead to infant nutrition deficiency or easy hunger, etc. Third, for infants aged 9-12 months, the interval between feeding formula and breast milk is generally 1-2 hours. Because the infant’s size and age are relatively large at this time, the interval should be shortened.