Baby diarrhea may be caused by germs infection, physical factors and improper feeding and other factors. 1. germ infection: can be divided into intestinal infection or extra-intestinal infection, intestinal infection is caused by viruses, bacteria, fungi and parasites. Extra-intestinal infections are mainly caused by upper respiratory tract infections, skin infections and other acute infectious diseases that release toxins that infect the intestinal tract. All of them may trigger diarrhea in babies. 2. Physical factors: if the baby’s digestive system is not yet mature, due to its gastric acid and digestive enzyme secretion is low, low enzyme activity, may cause excessive burden on the stomach and intestines, thus triggering diarrhea. 3. Improper feeding: is a more common cause of baby diarrhea, if the feeding process suddenly change the food varieties or too early to let the baby eat a lot of starch, fruits and vegetables, etc., may produce stimulation of the baby’s gastrointestinal tract, diarrhea. Therefore, if the baby diarrhea has not been improved, it is recommended to take the baby to the hospital in time to check, to clarify the cause of the disease, for treatment.