The baby spit up milk is watery may be imperfect development, improper feeding and other physiological factors, or functional dyspepsia, gastroesophageal reflux and other diseases. 1. physiological factors: due to the baby’s age, the vomiting center development is not yet perfect, poor coordination of swallowing muscle groups, so there will be spit up like water. If the breastfeeding speed is too fast, or the baby swallowed a lot of air, also prone to this situation, are normal physiological phenomena. 2. Functional dyspepsia: The basic causes of this disease include high visceral sensitivity, excessive stomach acid, Helicobacter pylori infection, heredity, eating too fast or irregular diet and other bad eating habits. Generally children will have poor appetite, spitting up, nausea, bloating and other symptoms, so there will be spitting up milk in the form of water. 3. Gastroesophageal reflux (GERD): The occurrence of this disease is mainly related to the decrease of esophageal clearing ability and mucosal resistance, as well as the impairment of anti-reflux structure and function. Common symptoms include heartburn, reflux, etc., and in some cases, it can be manifested as a baby spitting up watery milk. There may be other causes for the baby to spit up watery milk, it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.