Infants and children aged 0-1 years can take calcium supplements through vitamin D supplementation, dairy products, sun exposure, and calcium supplements. 1. Vitamin D: Oral supplementation with 400 IU of vitamin D per day is usually recommended for full-term infants. Preterm babies, twins, low birth weight babies are recommended to supplement 800IU vitamin D. Vitamin D is necessary for the growth and development of the child, if the lack of it can be irritable, excessive sweating, bone development abnormalities and other manifestations. 2. Dairy products: Dairy products are rich in calcium, which can be supplemented through breast milk and milk powder. 3. Sunbathing: Proper outdoor sunbathing can promote the absorption of calcium, but avoid sunburn caused by prolonged outdoor exercise. 4. Calcium supplementation: If the child shows obvious signs of calcium deficiency, he/she should go to the hospital and take calcium tablets, such as calcium citrate, according to the doctor’s instruction. Specific should follow the doctor’s instructions for supplementation.