There are many causes of vomiting in 3-5 year old children, commonly caused by gastrointestinal infections, organic obstruction of the digestive tract, and central nervous system diseases. 1. Infectious diseases of the digestive tract: such as gastritis, appendicitis, gastroenteritis, pancreatitis, etc., when the intake of unclean food, sometimes the gastric mucosa will appear inflammation, resulting in spasm, contraction of the stomach wall and thus vomiting. 2. Organic obstruction of the digestive tract: such as esophageal atresia, congenital esophageal stenosis, congenital megacolon, anal atresia, intussusception, pyloric obstruction, gastric torsion, intestinal torsion, etc., the contents of the gastrointestinal tract can not be discharged through the intestinal lumen, which leads to nausea and vomiting. 3. Central nervous system diseases: meningitis, intracranial space-occupying lesions, intracranial hemorrhage, etc. Diseases such as meningitis can affect the nervous system, which can produce lead to vomiting, and vomiting is projectile. Vomiting in 3-5 year old children may also have other causes, it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.