Due to the increasing needs of physical development, breastfeeding alone cannot fully meet the nutritional needs of growth and development of 4-month-old infants, so most infants need to add complementary foods at 4-6 months. The principle of adding complementary foods is from less to more, from fine to coarse, from thin to thick, from one kind to many kinds, starting from liquid, then semi-liquid, and finally to solid food, so that infants can gradually adapt to the gastrointestinal function from mouth to mouth. It is recommended to eat egg yolk, soft noodles, green vegetable juice, carrot puree, apple puree, mashed potatoes, rice flour, etc.; avoid adding meat, seafood, drinks, seasonings, etc., which are not conducive to the digestion and absorption of infants, and may even have allergic symptoms, and allergy-prone fruits should also be avoided, such as mangoes, pineapples, etc. In the process of adding complementary foods, if the infant refuses to eat a certain food, parents should not force, can try again every other day, usually after several attempts the infant can accept. If the infant has abnormal stools, the complementary food should be suspended, and the original amount or a small amount should be tried again after normal bowel movements. When infants are sick, supplementation should be suspended to avoid increasing the burden on the gastrointestinal tract. It is recommended to add complementary foods for the first time in the morning, and to seek medical attention in case of discomfort.