Patients with black, dilute stools consider three factors, as follows: First, dietary factors: eating a lot of greasy, high-protein food, slow evacuation of stool, black stools will appear, while more smelly. Second, consumption of certain drugs or food: stool staining, such as bismuth, iron, Chinese medicine, or eating animal blood, animal offal, will appear stool color changes. Third, bleeding: alert to the occurrence of gastrointestinal bleeding, if the consideration of gastrointestinal bleeding should be given high priority, adults with daily bleeding greater than 5mL, fecal occult blood is positive, but the naked eye view of the stool is still yellow, if the amount of bleeding greater than 50mL, it can appear black stool or tarry stool. When black, thin, paste-like stools are present, an increase in bleeding should be considered. There are many clinical causes of gastrointestinal bleeding, including peptic ulcer, ruptured esophagogastric-fundus varices, erosive gastritis, and gastric cancer. It is important to seek medical attention in a timely manner and give comprehensive examination and treatment under the guidance of a doctor to avoid delaying the condition.