A one-year-old baby’s green stool may be caused by physiological factors, lactose intolerance, indigestion and other factors. 1. Physiological factors: in the parents to the child to add complementary foods during the intestinal flora will make part of the bilirubin into bilirubin, discharged stool is light green, there is no other abnormalities in the performance of the phenomenon, is a normal phenomenon. 2. Lactose intolerance: when a one-year-old baby lactose intolerance exists, it will also lead to green stool color, may also be accompanied by bloating, abdominal cramps, diarrhea and other symptoms. 3. Indigestion: consuming a lot of cold and greasy food or having a cold abdomen may trigger indigestion, which can lead to green stools, and may be accompanied by abdominal distension and abdominal pain and other symptoms. A one year old baby with green stools may also be the presence of other disease factors, parents are advised to take their children to the doctor for timely examination and treatment.