Half yellow and half black stools may be caused by dietary factors, medication factors, gastrointestinal bleeding and other reasons. 1. Dietary factors: Eating black food, such as fungus, black sesame, black beans, etc., or eating animal blood products, such as pig’s blood, chicken blood, etc., half yellow and half black stools can occur. 2. Drug factors: taking bismuth (colloidal bismuth, etc.), iron supplements (ferrous sulfate, ferrous gluconate, etc.) can appear half yellow and half black stools. 3. Gastrointestinal bleeding: for example, chronic gastritis, peptic ulcer bleeding, because the amount of bleeding is relatively small, and the intestinal tract through the oxidation of the formation of sulfide, resulting in the discharge of half yellow and half black stools, usually accompanied by stomach pain, nausea, acid reflux symptoms. Half yellow and half black stools are recommended to consult a doctor to clarify the cause of the disease, and if necessary, to give treatment under the guidance of the doctor.