The reasons for 3 month old baby vomiting are as follows: 1, may be due to eating too much milk, eat milk not digested or abdominal cold caused by gastrointestinal discomfort caused by vomiting, at this time parents can give the baby abdominal heat compress, and at the same time to assist the navel as the center of the clockwise abdominal rubbing to promote gastrointestinal peristalsis, can be oral mamma love or lactobacillus granules to adjust the intestinal flora, reduce the amount of milk each feeding, so that the gastrointestinal to get a certain recovery. 2. If the vomiting is accompanied by poor mental state and obvious abdominal distension, you need to take your baby to the hospital for a detailed examination, it may be a surgical disease, such as intestinal obstruction or intestinal overlap, which requires further treatment under the guidance of the hospital doctor’s detailed examination.