Breast pain in a nine-year-old girl may be a normal physiological phenomenon, or it may be caused by pathological factors such as trauma or breast disease. 1. Normal physiological phenomenon: 9~12 years old girls enter puberty, the body estrogen secretion increases, the breast will gradually develop, accompanied by a slight pain, this is a normal physiological phenomenon, no need to be treated. 2. Pathological factors: (1) trauma: if a nine-year-old girl’s breast is hit by an external force, there may be painful symptoms, parents can use a towel to apply a hot compress, which can promote blood circulation, promote the dissipation of bruises in the breast, and alleviate the pain symptoms. (2) Breast diseases: such as breast hyperplasia. It is due to some reasons caused by endocrine hormone metabolism imbalance, resulting in increased levels of estrogen in the body, accompanied by breast pain and swelling and other phenomena, nine-year-old girl breast pain may be due to breast hyperplasia, it is recommended to consult the hospital in a timely manner, under the guidance of the doctor’s treatment. If a nine-year-old girl has symptoms of breast pain, parents are advised to take their children to the hospital to do the relevant examinations and do a good job of physical conditioning measures.