The child’s crying during breastfeeding is considered to be related to physiological factors such as improper breastfeeding posture and insufficient breast milk, as well as indigestion and mouth ulcers. 1. Physiological factors: improper posture during breastfeeding, insufficient breastmilk to meet the child’s needs, defecation or bowel movement during breastfeeding, etc. may cause the child to cry during breastfeeding. 2. indigestion: when the child gastrointestinal dysfunction, stomach to food tolerance diastolic function decreased indigestion, the child may be full after meals, middle and upper abdominal pain and other symptoms of discomfort and milk crying phenomenon. 3. Mouth ulcers: the cause of the disease is not clear, may be related to genetic factors, immune factors. When the child has mouth ulcers, it can be manifested as restlessness, local lymph node swelling, oral mucous membrane damage with a slight pain. When a child is breastfeeding, milk irritation of the oral mucosa can be manifested as crying at breastfeeding. There are many reasons why children cry at breastfeeding, such as mosquito bites, gastroenteritis, thrush, pneumonia and so on. If the child has a long-term phenomenon of crying at the breast, parents should take it to the doctor in a timely manner.