1.Detailed medical history is important to understand the duration and urgency of vomiting; the mode, amount, nature and smell of vomiting; the relationship with diet; whether vomiting is accompanied by nausea, duration and severity; whether there are other abdominal symptoms such as abdominal pain, bloating, blood in stool, vomiting blood, etc.; whether accompanied by headache, dizziness, vertigo, vision and hearing changes, tinnitus; whether there is hepatitis, nephritis, history of diabetes, history of abdominal surgery, history of drug use, etc. History of drug use. 2, careful physical examination: pay special attention to the presence of abdominal bulging, abdominal muscle tension, pressure pain, rebound pain, stomach type, intestinal type, gastrointestinal peristaltic waves, the presence of masses, watery sound, mobile turbid sounds, intestinal sounds are normal. It is also necessary to pay attention to the patient’s psychoneurological status, the presence of dehydration signs, the presence of jaundice, neurological examination and, if necessary, fundus examination. 3.Targeted examinations: general blood, urine, fecal routine, urine ketone body, blood potassium, sodium, chloride and blood gas analysis; liver function, kidney function, electrocardiogram, chest X-ray according to the specific situation of the child; abdominal fluoroscopy and abdominal plain film, barium meal gastrointestinal imaging, barium enema imaging, gastrointestinal endoscopy, 24-hour esophageal pH monitoring, abdominal ultrasound, and even abdominal CT, MRI if necessary; cranial organ pathology is considered. For those who consider intracranial infection, cerebrospinal fluid examination should be done as soon as possible, and for those who have recurrent vomiting, cranial CT and electroencephalography should be performed to exclude intracranial occupying lesions and other neurological diseases; 4. Diagnosis of recurrent vomiting must exclude digestive system, neurological diseases and systemic diseases.