A two-year-old baby vomiting yellow water may be caused by improper diet, acute gastritis, pyloric stenosis and other reasons. 1. Improper diet: when the baby eat too much food or eat spoiled food, it may increase the burden on the stomach, easily cause indigestion and lead to vomiting, when the baby vomiting is more serious, it may appear to vomit yellow water. 2. Acute gastritis: acute gastritis is an acute inflammatory lesion of the gastric mucous membrane injury, is a common digestive system diseases, the main clinical manifestations of epigastric discomfort, bloating, nausea, vomiting, acid reflux and other symptoms, when the baby’s condition is more serious, it may cause vomiting yellow water. 3. pyloric stenosis: pyloric stenosis refers to the pyloric sphincter highly hypertrophic hyperplasia, resulting in obstacles to the passage of food and gastric juices, the patient’s main manifestations of vomiting, abdominal pain, loss of appetite and other symptoms, when the patient vomiting serious, may also cause vomiting yellow water. Two-year-old baby vomiting yellow water, there may be other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.