The treatments for malnutrition in a 3.5 year old child can be categorized into general treatment, basic medication and so on. 1. General treatment: (1) remove the cause of the disease, treat the original disease: malnutrition in older children is mostly caused by the continuation of malnutrition in infancy, or certain disease factors such as chronic wasting disease that increases catabolism, digestive tract anatomical function abnormality caused by digestive and absorption disorders, and so on. Therefore, it is necessary to ensure the intake of high-quality protein, early correction of congenital malformations, and eradication of various consumptive diseases. (2) Adjustment of diet: malnutrition can also be caused by bad eating habits, such as partiality and picky eating, etc. Therefore, we should pay attention to the nutritional balance of daily diet. (2) Basic medication: you can choose some nutritional supplements suitable for children under the guidance of doctors, such as taking various vitamins and trace elements orally. Once malnutrition occurs, parents should bring their children to the hospital in time to correct it and prevent it from affecting the growth and intellectual development of the children.