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 psychology and behavior. The earliest sign of puberty is the enlargement of testicles, followed by the increase of androgens, secondary sexual symptoms and accelerated growth; the average duration of puberty for boys is 4.9 years, with a total height growth of about 25-30 CM. 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, including about 1 year in the middle of puberty, which is also a period of rapid growth, with an annual growth rate of nearly 10 CM. after the onset of menarche, the growth rate decreases sharply, and continues to grow for a total of about 4-8 CM. after two years of menarche, girls are generally no longer likely to grow taller. Some normal girls do not have an obvious rapid growth period (because rapid growth period is often also a period of rapid bone 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 two years of bone growth is not better than a 6 cm growth in one year and only one year of bone growth). Normal puberty initiation is an extremely complex process that is the result of the interaction of multiple hormones and many neurotransmitters. The pubertal onset process is currently considered to be 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. The appearance of secondary sexual characteristics in girls before the age of 8 or the onset of menstruation before the age of 10, and the appearance of secondary sexual characteristics in boys before the age of 9, accompanied by excessive physical growth, are called precocious puberty.