Vitamin D deficiency in babies, also known as vitamin D deficiency rickets, is a high-risk group for infants and young children, especially small infants. Vitamin D deficiency disrupts calcium and phosphorus metabolism, resulting in a chronic nutritional disease characterized by bone lesions throughout the body. Vitamin D deficiency in babies is mainly manifested as skeletal changes in the fastest growing parts of the body, and can also affect muscle development and cause changes in neuroexcitability. Early manifestations are mostly seen within 6 months of age, especially in infants within 3 months of age, and the main manifestations are increased neuroexcitability, for example, babies are easily irritated, irritable, crying, and shaking their heads due to excessive sweating and scalp stimulation, all of which are non-specific symptoms. During the active phase, the child’s skull grows rapidly within 6 months of age, mainly because of the softening of the skull and the late closure of the fontanelle. 6 months later, the child’s skull is squared, the rib cage is beaded, the chest is cocked or funneled, the Hao’s sulcus, and in severe cases, the spine may be backward curved or scoliosis with pelvic deformities. The extremities may show symptoms such as bracelets, ankle bracelets, X-leg and O-leg. In more severe cases, the child may also have ligamentous laxity, decreased muscle tone and strength, malnutrition and anemia, and enlargement of the liver and spleen. In the recovery period, clinical symptoms and signs gradually decrease or disappear, and irregular bands of calcification can be seen on X-ray. The sequelae phase is mostly seen in children over two years of age and can have residual skeletal deformities of varying degrees. Vitamin D deficiency rickets may affect the growth and development of children, so children should take vitamin D supplements on time after birth, have enough outdoor activities, and once diagnosed, active treatment is needed, mainly to control the activity period and prevent skeletal deformities.