One year old baby diarrhea may be caused by improper diet, or may be caused by acute enteritis, typhoid fever and other diseases. 1. Improper diet: Because the baby’s gastrointestinal function is not yet perfect, if eating too fast, eat cold food, may stimulate the gastrointestinal mucosa, the situation of dilute stool. If it is not accompanied by other uncomfortable symptoms, it is a normal phenomenon. 2. Acute enteritis: Acute enteritis may be caused by pathogenic microbial infection, low immunity and other factors. The child will have diarrhea, or accompanied by fever, nausea, vomiting and other symptoms, manifested in the one-year-old baby diarrhea. 3. Typhoid fever: Typhoid fever is an acute intestinal infectious disease caused by Salmonella typhi infection. Affected children mainly manifested as abdominal pain, diarrhea, etc., can appear one-year-old baby dilute stool. One year old baby diarrhea may also have other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.