It is generally not recommended to add complementary foods for 4-month-old babies. It is recommended to add complementary foods after 6 months of age, which requires gradual and orderly progress, attention to moderation, and comprehensive and balanced nutrition. It is generally recommended to add complementary foods only at 6 months of age. Foods that are easy to swallow and digest and not likely to cause allergies, such as iron-fortified rice powder and pureed vegetables, can be added. If weight gain is poor, there is a desire to eat, appear to open their mouths and wait for food, and can safely accept and swallow complementary foods, it is also possible to start adding complementary foods based on breastmilk. At the beginning, you can choose iron-fortified cereals, such as iron-fortified rice powder, etc. Vegetables such as white radish, carrot, spinach puree, etc., and fruits such as apples, bananas and pears. It is recommended to let children move the food to the back of the mouth by their own oral movements, as it is easy to cause nausea and vomiting if the food is delivered directly to the back end of the tongue. At the beginning, usually 1 time a day, rice flour or vegetable and fruit puree 1-2 spoons each time, each time to add only one kind of complementary food, pay attention to observe the infant after consumption of allergic reactions, if 5-7 days without adverse reactions and then add another kind.