Constipation in children over the age of three may be caused by dietary habits, indigestion or pediatric sigmoid colon redundancy. It can be treated by improving diet, massage or surgery according to different situations. 1. Dietary habits: Children who are anorexic, picky eaters or partial eaters for a long time will consume too little fiber, which will lead to constipation. You can give your child more to eat something containing crude fiber, such as such as buckwheat, oats, corn, etc., can promote human digestion, promote human defecation. 2. Indigestion: more than three weeks old child gastrointestinal function development is not complete, if the food intake is too much, it may lead to indigestion, constipation. You can give the baby to do clockwise abdominal massage can promote gastrointestinal peristalsis, accelerate the discharge of stool. 3. Pediatric sigmoid colon length: sigmoid colon length is generally more than 40-60 belongs to the pediatric colon length, the main symptoms are constipation, abdominal distension and so on. The main symptoms are constipation, abdominal distension, etc. It can be treated by surgery, and can reach the clinical slowdown. There are many other causes of constipation in children over three weeks old, it is recommended to consult a doctor in time, with the help of the doctor to clarify the cause of the disease, and targeted treatment or therapy.