Four-month-old babies’ green stools from breastmilk are usually caused by imperfect digestive function, cold abdomen, lactose intolerance and other factors. 1. Imperfect digestive function: the digestive function of infants and young children is not yet perfect, can not completely digest breast milk, resulting in green stools, as the digestive system function is perfect, the symptoms will disappear. 2. Cold abdomen: If the abdomen of infants and young children is cold, it will stimulate the gastrointestinal peristalsis to increase, the food in the stomach to shorten the stay time, can not be decomposed and absorbed, the green stools. 3. Lactose intolerance: If the infant’s body lacks the enzyme lactase, it is easy to cause lactose intolerance, resulting in the infant’s green stools, and the stools can be manifested as eggdrop soup, accompanied by a sour odor. Four months baby pure breast milk green stools, there may be other reasons, it is recommended to go to the hospital, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.