Complementary foods can usually be started at 4-6 months of age. For exclusively breastfed infants, it is recommended to add complementary foods after 6 months, while for non-exclusively breastfed infants, it is recommended to add complementary foods after 4 months. The time to add complementary foods is not only related to whether the baby is exclusively breastfed or not, but also related to the baby’s digestion and absorption function. If the baby’s stool does not change significantly after the addition of complementary foods, it means that it is possible to start adding complementary foods, and the amount should be increased gradually from less to more. However, if the baby has a long-term change in stool characteristics and other digestive reactions, it is necessary to extend the time to add complementary foods. The addition of complementary foods can not only supplement the nutrition required by the baby’s body, but also exercise its chewing and swallowing ability. If the baby does not have sufficient practice in chewing, feeding difficulties may occur after the first year of age. In addition, the addition of complementary foods should follow the principles of less to more, from thin to thick, from one to many, from fine to coarse, from simple to complex.