The baby 6 months spitting up may be caused by developmental immaturity, but also may be caused by acute gastroenteritis and so on. 1. Developmental immaturity: 6 months baby spitting up is mostly considered to be the vomiting center and swallowing muscle group development immaturity caused by, and the baby’s stomach capacity is small, was horizontal, the lower esophageal sphincter relaxation, pyloric sphincter developed, easy to cause the baby spitting up the performance. 2. Acute gastroenteritis: Acute gastroenteritis may be caused by viral infection, bacterial infection, parasitic infection and other reasons. Patients will have abdominal pain, diarrhea, nausea, vomiting and other manifestations. Therefore, 6-month-old babies with acute gastroenteritis will have the symptom of spitting up. 3. Other: 6 months baby spitting up may also be meningitis, gastroesophageal reflux and other causes. The baby 6 months spit up may also have other causes, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.