Adults with dark green stools may be related to the food consumed, especially the consumption of green vegetables, blood clots, or other foods or medications that are black or green in color. If food or drugs are excluded, it is necessary to consider whether there is the possibility of gastrointestinal bleeding, and it is recommended to improve the fecal occult blood test. If it is positive, it is necessary to complete the gastroenteroscopy to exclude digestive tract lesions, the possible diseases are mainly inflammation, ulcer or tumor. If necessary, it is also necessary to complete the examination of Helicobacter pylori, abdominal ultrasound or CT, etc. It is recommended to avoid food or drug factors before the fecal occult blood test.