Precocious puberty is defined as the age at which any of the sex characteristics appear 2 standard deviations earlier than the average age of the normal population. It is now generally accepted that precocious puberty can be diagnosed as the development of secondary sexual characteristics or the onset of menstruation before the age of 8 for girls and the onset of sexual development before the age of 9 for boys. Since sexual development is related to a variety of factors and human growth and development is a continuous process, there is no very precise limit. Precocious puberty often affects the physical and mental health of adolescents, while their intellectual development is generally normal. Precocious puberty in females can easily become the target of sexual aggression and even pregnancy. Individual precocious puberty also does not exclude tumor factors. The hazards of precocious puberty: 1. Children with idiopathic precocious puberty are affected by sex hormones in the body, with premature acceleration of physical growth, early epiphyseal fusion, shortening of the growth period, and early cessation of growth, resulting in a final adult height lower than the height of normal children of the same age who develop according to normal puberty. 2, precocious puberty, but the psychological and intellectual development of children is still the actual age level, premature appearance of sexual signs and development of reproductive organs will lead to immature children psychological disorders, will have low self-esteem, autism, but also bring a lot of inconvenience to life, serious cases even affect reading and learning. There are many causes of precocious puberty, which can be divided into central (true) and peripheral (pseudo) according to whether the hypothalamus-pituitary-gonadal axis function is activated in advance. (a) Central precocious puberty (CPP), also known as true precocious puberty, is due to premature activation of hypothalamic-pituitary-gonadal axis function and secretion of GnRH pulses, and the affected children have the development of ovaries or testes in addition to the development of secondary sexual characteristics. The process of sexual development follows the same sequence as normal pubertal development. Only the age is advanced. The main causes include organic lesions secondary to the central nervous system and idiopathic precocious puberty. Idiopathic precocious puberty, also known as somatic precocious puberty, is caused by the hypothalamus’ decreased sensitivity to the negative feedback of sex hormones, resulting in premature secretion of gonadotropin-releasing hormone, which is more common in females and accounts for more than 80% of girls’ CPP, while only about 40% of boys. 2.Precocious puberty secondary to central nervous system abnormalities, including: ① tumor or occupying lesion: hypothalamic malformation tumor, cyst, granuloma, ② central nervous system infection, ③ acquired injury: trauma, post-operative radiotherapy or chemotherapy, ④ developmental abnormalities: hydrocephalus, optic septal hypoplasia, etc. 3, other diseases: primary hypothyroidism. (B) Peripheral precocious puberty is also called pseudoprecocious puberty. It is not controlled by hypothalamus-pituitary and gonadal function, there is secondary sex characteristics development, there is elevated level of sex hormones, but hypothalamus-pituitary-gonadal axis is not mature, no gonadal development. 1, gonadal tumors: ovarian granulosa-vesicular membrane cell tumor, luteinoma, testicular mesenchymal cell tumor, teratoma, etc. 2, adrenal gland diseases: adrenal tumors, congenital adrenal cortical hyperplasia, etc. 3.Exogenous: such as estrogen-containing drugs, food, cosmetics, etc. 4.Other: McCune-Albright syndrome. (3) Some precocious puberty is simple premature breast development, simple premature pubic hair development, simple early menarche. (4) Some precocious puberty is due to the appearance of tumors in the body, which can secrete substances similar to sex hormones. Sometimes, when the tumor is still small, the amount of sex hormones it secretes is already large enough to cause sexual development, so children with precocious puberty must see a doctor in time for early diagnosis and treatment.