The color of normal stool is yellowish-brown. Black green stool is mainly seen in the following cases: 1, related to diet, such as eating green vegetables, because the chlorophyll in green vegetables will not be completely digested during digestion, so the stool is black green. 2, related to the acidity in the gastrointestinal tract, if the gastrointestinal tract is an acidic environment, the digested food residue can be green. 3, indigestion, when the gastrointestinal tract dysfunction caused by indigestion. The stool is dark green because the food is not digested by the digestive juices. 4, when enteritis, due to pathogenic bacteria infecting the intestine, resulting in intestinal mucosa congestion, edema, thin stool, its discharge of dark green stool with mucus. 5, drug factors, such as antibiotics, oral gentamicin can appear after the stool is dark green. 6, a small amount of bleeding in the gastrointestinal tract can also appear when the stool is brown-green.