The time and dosage of calcium supplementation for 0-6 months old babies need to be determined according to whether they are full-term and full-weight babies, and cannot be generalized. Calcium deficiency in babies aged 0-6 months is mainly manifested as night terrors and crying, easily startled and other neurological symptoms, and if the calcium deficiency is prolonged, occipital baldness can occur, and in serious cases, hypocalcemia, rickets, malnutrition and other diseases. Calcium supplements should be accompanied by vitamin D to promote better absorption of calcium. Calcium and vitamin D supplementation should be started 1 week after birth for premature low birth weight babies and twins, and changed to preventive doses after 3 months; calcium and vitamin D supplementation should be started 2 weeks after birth for full-term babies. The best time of day for calcium supplementation is 1 hour before bedtime or after dinner, when there is less stimulation to the gastrointestinal tract and better absorption can be achieved. In addition, it is recommended that parents take their babies outdoors in the sun, as ultraviolet light exposure to the skin can better promote vitamin D synthesis, thus promoting calcium absorption.