Adolescence is an important period of transition from childhood to sexual maturity and the eventual acquisition of reproductive capacity, the last stage of child development, and the second peak of height growth. It is characterized by the rapid development of sexual organs and secondary sexual characteristics and the acceleration of physical development, and is accompanied by corresponding changes in psychological and behavioral aspects. The earliest sign of puberty is the enlargement of testicles, followed by the increase of androgens, secondary sex disorders and accelerated growth; the average time of puberty for boys is 4.9 years, with a total height growth of about 25-30 CM, of which, about 1.5 years in the middle of puberty, this period is a rapid growth period, with an annual growth rate of more than 10 CM, after which the growth rate decreases sharply, until it stops growing completely. The growth rate decreases until it stops completely. When a boy’s beard appears on his jaw, there is usually no more room for growth. The earliest sign of puberty is the enlargement of the ovaries (which is difficult to detect in time without ultrasound and is often marked by the development of breasts), followed by an increase in estrogen, the appearance of secondary sex characteristics and accelerated growth. The average length of puberty for girls is about 4.7 years, with a total height growth of about 20-25 CM, of which about 1 year is the middle of puberty, which is also the rapid growth period, with an annual growth rate close to 10 CM. after the appearance of menarche, the growth rate decreases sharply, and continues to grow about 4-8 CM. after two years of menarche, girls generally have no possibility to grow taller. Some normal girls do not have an obvious rapid growth period (because the rapid growth period is often also a period of rapid bone age growth, therefore, the absence of rapid growth period is not necessarily a bad thing. If there is a rapid growth period, a 10 cm growth in one year and a two year increase in bone age is not better than a 6 cm growth in one year and only a one year increase in bone age). Normal puberty initiation is an extremely complex process that is the result of the interaction of multiple hormones and many neurotransmitters. It is currently believed that the pubertal onset process is the result of a networked interaction of a series of neuro-endocrine regulatory factors controlled by the central nervous system. However, the causes and mechanisms of pubertal development initiation are still not fully understood. In girls, secondary sexual characteristics appear before the age of 8 years, or the first menstruation occurs before the age of 10 years; in boys, secondary sexual characteristics appear before the age of 9 years, accompanied by excessive physical development, which is called precocious puberty.