The reason why a three or four year old child says that his stomach hurts and vomits is because of a digestive tract infection, indigestion, food poisoning and other factors. 1. digestive tract infection: the reason why three or four year old children have a stomach ache is not excluded due to gastritis caused by Helicobacter pylori infection, which belongs to the digestive tract infection, in addition to nausea and vomiting and other symptoms, will be accompanied by acid reflux, heartburn and other symptoms, so there will be a stomach ache and vomiting performance. 2. indigestion: if three or four year old children eat irregularly, often overeat or eat spicy and irritating food, may increase the burden on the stomach and intestines, resulting in symptoms of indigestion, such as stomach pain and vomiting. The three or four year old child said stomach pain and vomiting situation, also does not rule out the existence of other causes, should be immediately to the hospital, with the doctor for examination, and then do targeted treatment and treatment.