The common causes of hard stools in babies include irrational dietary structure, constipation and congenital abnormalities of intestinal development. 1. Unreasonable dietary structure: If the breastfeeding mother’s daily intake of protein content is high, resulting in a high proportion of protein in breast milk, this breast milk is drank by the baby into the digestive tract, its low digestive function can not be completely broken down by protein, protein deposits in the intestinal tract will form hard stools. 2. Constipation: If the baby is constipated because of drinking too little water, holding his stool or dietary stimulation, etc., the stool that is not discharged in time stays in the gastrointestinal tract and becomes dry and hard when it is drained of water. 3. Congenital abnormalities of intestinal development: congenital abnormalities of intestinal development, including megacolon and redundant colon, can lead to a relative increase in the contact time between the feces and the intestinal mucosa, and the water in the feces is over-absorbed by the intestinal tract, and the baby will have hard stools. If your baby’s symptoms of hard stool are severe, or if the symptoms persist and do not improve, you should take your baby to the hospital in time for consultation and treatment.