The reasons why newborns always have watery diarrhea include: imperfect intestinal development, abdominal cold or indigestion, lactose intolerance, and bacterial viral infections. As the intestinal tract of newborns is still developing, some of its functions are imperfect, the number of intestinal peristalsis is high, and the absorption function of the intestinal tract is poor, which may lead to the situation that newborns always have diarrhea. If the newborn is not carefully looked after, it may cause the child to suffer from abdominal cold or indigestion, which may cause symptoms of diarrhea. Since some newborns may have intestinal lactose intolerance, they may experience diarrhea after breast milk or some formula. If a newborn’s gastrointestinal tract is infected by bacteria or viruses, it may lead to viral or bacterial enteritis, which can lead to the condition of always having diarrhea. There may be other reasons for newborns always having diarrhea, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.