For girls who have menstruation at the age of nine, there may be precocious puberty, which should be treated according to the different types of precocious puberty through general treatment, medication, surgery and other ways of treatment. 1. Central precocious puberty: caused by the early development of the hypothalamic-pituitary-gonadal axis, in which case gonadotropin-releasing hormone agonists such as leuprolide and goserelin can be used for treatment according to the doctor’s instructions. 2. Peripheral precocious puberty: in this case, the hypothalamic-pituitary-gonadal axis function of the girl is normal, but due to gonadal tumors, adrenal gland diseases or exogenous substances leading to increased levels of sex hormones in the body: (1) If it is caused by gonadal tumor or adrenal gland disease, then it is necessary to follow the doctor’s instruction to actively treat the original disease through surgery or other means; (2) If it is caused by exogenous factors such as diet and medication, parents should pay attention to reduce the intake of estrogen-rich foods and also be careful not to let the child accidentally consume estrogen and progesterone preparations. 3. Incomplete precocious puberty: this type is a special type of precocious puberty, due to the function of hypothalamus-pituitary-gonadal axis is partially activated, the patient is only manifested as simple breast development, the onset of menstruation, etc. At this time, it is recommended that the girl should exercise properly and develop good habits, parents should pay attention to strengthen the communication with the child to reduce the psychological pressure.