A small section of hard black stool may be related to food, drugs, gastrointestinal bleeding, and different treatments should be taken according to different causes. 1. Food factors: food containing iron or melanin will cause black stool, such as animal blood, offal, sesame seeds, black beans, black rice, fungus, mulberry, etc., a large number of consumption of incomplete digestion of stool color black, too much to eat high-fat and high-protein food stool will be relatively hard, you can drink plenty of water, light diet. 2. Drugs: black stools caused by bismuth potassium citrate, iron and other darker color, you can stop the drug and observe, if still black stools alert gastrointestinal hemorrhage, cause hard stools scopolamine, belladonna tablets, calcium tablets, etc., pay attention to the dosage and usage. 3. Gastrointestinal bleeding: black stool is common upper gastrointestinal bleeding, such as ulcers, tumors, etc., the amount of blood is not a lot, the bleeding time is relatively short, the stool is black, if the amount of bleeding is large, the stool is red, you need to check the gastrointestinal microscope, you need to be based on the cause of the treatment, oral omeprazole enteric-coated tablets, magnesium alumina carbonate tablets to inhibit acid gastric protection, surgical bleeding control, if necessary. If you have black hard stool, timely medical treatment, the doctor to identify the cause of the clear diagnosis, guidance for treatment, do not unauthorized use of drugs, so as not to cause adverse.