1.Insufficient diet. When eating too little, the food residue is small. When the amount of sugar in the milk is not enough intestinal peristalsis is weak, can make the stool dry. 2, improper food composition. High protein content, insufficient carbohydrates, less intestinal content fermentation process, the stool is easy to alkaline, dry. 3.Do not defecate on time. Small babies live irregularly or hold stool for various reasons, lack of regular bowel training, unable to form a good bowel reflex. 4, severe constipation perhaps because of the lack of intestinal ganglion, congenital megacolon, parents should be aware of this, take the baby to the hospital for examination. 5, anal fissure anal pain during defecation, baby afraid of stool, psychological factors, vicious circle, parents should carefully observe, early medication.