Generally speaking, most children, girls at the age of 10 years old, boys at the age of 12 years old, the second sex characteristics, six months after the “jump”. Some girls have enlarged breasts or pubic hair or armpit hair before the age of 8, and boys have enlarged penis and testicles before the age of 9. Parents should pay attention to this, especially because the development of sexual characteristics in boys is more hidden, parents can not easily find out, and wait until the change of voice to seek medical attention, often missing the best treatment time. If a girl has one or more secondary sexual characteristics, such as breast enlargement, pubic hair and axillary hair growth, before the age of 8, or the first menstruation before the age of 10, or if a boy has an enlarged penis and testicles, pubic hair growth and voice change before the age of 9, then it is precocious sexual development. The child with precocious puberty will jump in height after half a year, higher than children of the same age, parents should not be happy too early. The child with precocious puberty often grows first and then does not grow, when other children grow, your child has stopped growing. Some adolescents have closed their bones at a very young age. Therefore, if you feel that your child has precocious puberty, you should go to the hospital for medical intervention as early as possible. If a girl’s height is not satisfactory two years after her menarche and a boy’s voice change, the intervention will be less effective. The hazards of precocious puberty are mainly psychological-behavioral and physical developmental. Children may have low self-esteem, fear and anxiety because they are physically different from their surrounding partners; girls with premature menstruation are often very nervous, which affects their normal life and study; children with precocious puberty often have accelerated skeletal growth while their sexual characteristics appear early, and their stature is temporarily higher than that of children of the same age, but due to early epiphyseal closure, their stature is shorter than normal in adulthood. Therefore, early treatment is needed to avoid the inferiority complex of the affected children and eventually obtain a satisfactory adult height.