Three-year-old baby pull black hard stool, common causes are constipation, diet or drug factors, gastrointestinal bleeding, parasitic infections, etc., need to clarify the cause of the disease and then symptomatic treatment. Common causes and treatments 1, constipation: reduce the number of bowel movements, at the same time, defecation difficulties, fecal dryness, long-term accumulation of fecal color deepening, serious anal fissure can occur. Daily habit of regular defecation, drink more water, regular diet, increase the high fiber content of food such as spinach, cabbage and fresh fruits, etc., can also follow the doctor’s advice to take lactulose to promote defecation; 2, diet or drug factors: such as taking bismuth, iron medication, can cause black stools. Consumption of large quantities of animal blood products such as pig’s blood can also lead to black stools. If it is caused by the above two reasons, there is no need to worry too much, such as stop taking bismuth, iron, animal blood products, by the intestinal emptying symptoms can disappear; 3, gastrointestinal bleeding: bleeding in the upper gastrointestinal tract is caused by the role of iron in the hemoglobin and intestinal sulfide, the formation of black ferrous sulfide. Lower gastrointestinal bleeding is because the blood stays in the intestines for too long, manifesting itself as black stools, which requires timely examination in the hospital for stool routine, occult blood test and stool culture. Once diagnosed with gastrointestinal bleeding, we should actively search for the cause of the disease, improve gastroscopy, enteroscopy and other tests if necessary, and use hemostatic therapy such as hemostasis, hemagglutinin and so on as prescribed by the doctor; 4. Parasitic infections: manifested as bulimia, polyphagia, decreased appetite, gastrointestinal dysfunction, and in severe cases, blood in the stool can be seen, we should do the routine examination of the fecal material to confirm the diagnosis, and follow the doctor’s prescription to clear the worms such as albendazole tablets and other treatments.