Malnutrition is directly or indirectly responsible for 60% of the annual deaths of children under 5 years old in China. It is mainly due to the lack of scientific feeding knowledge of parents, so scientific feeding is the key element to ensure and promote the healthy growth of children and reduce the rate of malnutrition. Infant and child nutrition is the foundation of a healthy body. Nutrition in infancy mainly comes from breast milk, but with age, nutrition will not be able to meet the needs of growth and development, at this time we should consider increasing some food nutrients, but the process can not be rushed, nutritional intake is a slow process, the need for food screening, not all nutritious food for infants and young children. Data show that 60% of the annual deaths of children under 5 years old in China are directly or indirectly caused by malnutrition. It is mainly due to parents’ lack of scientific feeding knowledge, so scientific feeding is the key element to ensure and promote children’s healthy growth and reduce malnutrition rate. The so-called infants and toddlers mainly refer to toddlers less than 12 months old and children aged 1-3 years old. Complementary food refers to any kind of supplementary food other than breast milk that contains nutrients and provides nutritional value to the child, whether in solid or liquid form. The addition of complementary foods (or weaning) is a gradual process, and this process mainly takes into account the child’s absorption, paying attention to the gradual nature of the food gradually, and following up with other foods after the transition is complete. The time of adding complementary foods directly affects the diet structure of infants and toddlers. Infants grow and develop rapidly, their digestive system gradually matures, and their stomach capacity increases. As much as possible, we should provide a variety of taste foods, so as to slowly develop and improve the taste system. The first change in diet structure is the change from breastfeeding to complementary feeding. Studies have found that the use of complementary foods for infants at 3 or 4 months of age decreases the quality of the infant’s body compared to the normal addition of complementary foods for infants and children, and increases the probability of diarrhea. Breast milk is natural, non-polluting, nutritious and suitable for infants and children to absorb, and has certain anti-bacterial factors to prevent foreign infections, as far as possible, in accordance with the doctor’s instructions, add complementary foods to children in a timely manner, but not too early. After 6 months of age to add complementary food infants and toddlers, due to the sense of smell, taste and chewing function of the development of exercise has been affected, found that with the growth of age, young children can appear a variety of picky anorexia, only prefer certain foods, aversion to the rest of the food, and even nausea. It has been found that 35% of young children are not sensitive to staple foods (cereals, starches, poultry, vegetables, etc.) and prefer only dairy products, especially interested in dairy drinks. The daily intake of dairy products can be 800-1200 ml. Although the daily protein intake is up to the standard, the structure is not reasonable, but it increases the burden on the gastrointestinal tract, followed by problems such as indigestion, accumulation of food and absorption. Another 30% of toddlers show a preference for softness of food. Due to late addition of complementary foods or inappropriate softness of food during infancy, they may refuse adult food in early childhood and prefer only liquid and semi-liquid. These children tend to be in good health at home and then develop certain digestive disorders when they enter early childhood institutions. Therefore, adding foods such as dairy, starch, fruits and eggs in a reasonable and orderly manner from 4-6 months of age is very beneficial to children’s dietary structure and growth and development, and it is important to note that the early or late time for infants to try solid foods depends on their digestive ability and appetite, and there are individual differences in each infant, so it is not advisable to make mechanical rules. Principles of complementary foods: The food chosen should be easy to absorb, meet the needs of growth, and not easy to produce allergies. The food selection should be based on the following principles: from thin to thick, from fine to coarse, from less to more, from single to complex, and accustomed to one and then add another. 4-6 months old infants are depleted of stored iron, so the choice of food should give infants iron supplements. The first thing to add is starchy staple foods, especially iron-fortified rice flour. Next, root and tuber vegetables and fruits are introduced, which can be supplemented with vitamins and minerals, followed by the gradual introduction of animal foods and soy products. Whether breast-fed or formula-fed, milk is still the basic food for infants, and the daily milk supply should not be less than 2/3 of the total energy (about 250 kJ/kg) for infants 6-8 months of age, and not less than 1/2 of the total energy (188-209 kJ/kg) for infants 10-12 months of age. There is a habitual process of food acceptance, which should range from 1 spoonful, 2 spoonfuls, multiple spoonfuls to a meal, one or two kinds to many kinds. Such as vegetable addition, that is, adapt to the first vegetable after a few days and then attract the second vegetable, each 3-7d. This can be found in infants allergic to food, but also to stimulate the development of the sense of taste, so that infants try to get used to different food taste opportunities. In the process of adding complementary foods, it often happens that infants show a preference for familiar things (dairy) and a fear of new tastes and textures, and even after eating, some children still experience nausea or even vomiting. After rejecting a new food 2-3 times, the infant is mistakenly thought to “not like it”, “can’t eat it”, “won’t eat it”, and thus stop adding the complementary food. This deprives the infant of the right to eat this complementary food and the opportunity to learn to eat new foods. Ninety percent of infants can quickly accept new foods, and another 10 percent can eventually accept each new food after first licking, reluctantly accepting, spitting out, and then repeatedly (10-15 times) feeding. Therefore, infants should be treated correctly “aversion to new” problem, patient repeated feeding, will change the infant’s fear of new food psychology. At the same time, food should be added to pay attention to the transition from fine to coarse, that is, mud, velvet (semi-solid food), froth, adult food (solid food); 6 months of age infants appear solid food backward to the function of the pharynx, and infants began to teething, the digestive system can secrete more digestive enzymes, kidney function gradually mature, at this time, solid food should be given at the right time, which is a key period in the development of human swallowing solid food function. If solid food is not fed late at 6 months of age, this ability will not be developed during the critical period and the infant’s ability to swallow solid food will decline. Therefore, after 7-8 months of age, food should be made into “fingers” or “strips” to facilitate infants’ grasping and gripping into the mouth to promote infants’ chewing and swallowing function development, which is also beneficial to dental development. To prevent picky eating, partial eating, refusal to eat and other undesirable eating behavior in the future, to lay the foundation for correct eating and balanced diet after 1 year old. As a result of oral dysplasia, children show uncoordinated biting-chewing-swallowing, and then refuse to eat solid and semi-solid foods or have difficulty eating foods. It makes the diet structure of young children change and becomes the main influencing factor of anorexia in children. By about 12 months of age, the oral jaw movements of young children produce the rotation of food in the mouth, which is important for grinding and biting fibrous foods and sensory foods. Therefore, in infancy and early childhood, especially in the first 12 months of life, food traits and feeding patterns should be gradually changed according to developmental status. Do not be too hasty, otherwise it will increase the burden on the infant’s body, resulting in delayed physical and mental development, which will have immediate and long term effects on their health. The suggestion to improve the addition of complementary foods: At present, breastfeeding is widely known, and although complementary feeding for infants and young children can be promoted from a certain level, due to the lack of awareness, there are often problems such as adding complementary foods too early or too late, less variety, poor quality, adding order and transition of traits, which make changes in the diet structure of infants and young children, thus affecting their growth and development. Therefore, timely and reasonable addition of complementary foods is necessary to ensure good growth and development of infants. Through continuous feedback and adjustment by feeding and caregivers and pediatricians, we can make infants and toddlers eat a wider variety of complementary foods, add them at a more reasonable time, consume more balanced nutrients, and optimize the structure of their diet, thus making them healthier, with better growth and development and nutrition.