Sudden vomiting in babies is a common problem that many parents may encounter. There are many reasons for this phenomenon, which can be simple poor digestion, gastroenteritis, or even a manifestation of influenza, surgical appendicitis, intussusception, and central nervous system infection may also cause sudden vomiting, so it is a common phenomenon but needs to be closely observed. The most common cause of vomiting is indigestion, whether it is caused by eating something inappropriate or by a decrease in digestive function due to a cold stomach, both internal and external causes can cause vomiting. Next is gastroenteritis, a viral or bacterial infection of the gastrointestinal tract, which is often accompanied by abdominal pain, or secondary diarrhea, so it may be effective to give the child something to digest and, if necessary, add anti-infective treatment. Some children can also exhibit sudden vomiting because of bad food or even food poisoning. So when vomiting suddenly, think about what your child has eaten in the last half day. In short, you should closely observe your child’s mental state, give him/her light saline or oral rehydration salt in small amounts, eat easily digestible food, observe the amount of urine, and go to the hospital if necessary.