Adolescent development is an important stage of life. With the development of socio-economic development, pubertal development shows a trend of continuous advancement, and the incidence of precocious puberty is increasing. The early onset of sexual development in children with precocious puberty has shortened the growth period of the affected children, resulting in the loss of adult lifetime height and the emergence of psychological problems in some of them, which has become a focus of concern for society and parents. Precocious puberty is defined as the onset of secondary sexual characteristics in girls before the age of 8 and in boys before the age of 9. Depending on whether the hypothalamus pituitary gonad axis (HPGA) is activated early or not, it is classified as central precocious puberty, peripheral precocious puberty, and partial precocious puberty. In this paper, we review the possible mechanisms underlying the increased incidence of idiopathic central precocious puberty. Recent surveys around the world have shown that the age of puberty has tended to advance over the past century, and the age of mammary gland development continues to advance, while the trend of early menarche in girls has slowed or stalled since the mid-20th century. The 1997 National Survey of Girls Aged 3 to 12 Years (PROS), covering 34 states in the United States, showed that the mean age of mammary gland development was (9.96 ± 1.82) years for whites and (8.87 ± 1.93) years for blacks, with -2 standard deviation (SD) ages of 6.3 and 5 years, respectively. between the 19th and mid-20th centuries, the age of menarche advanced from 17 to 14 years for girls in the United States and Western European countries. The trend of increasingly early pubertal development has slowed or even stalled after the middle of the 20th century. For example, in the United Kingdom, Switzerland, and Belgium, the age of menarche has instead shifted back by 0.14 to 0.03 years, while in the United States, the age of menarche of girls surveyed from 1973 to 2001 decreased very little, from 12.8 to 12.5 years. China is a vast country, and the natural environment, climatic conditions and economic development of different regions vary greatly. In 2002, a survey in Shanghai reported that the age of onset of breast development in girls was 10.2 ± 1.8 years, which was only half a year earlier than 20 years earlier. 2004 epidemiological survey in Beijing showed that the age of onset of breast development in females was 9.5 ± 1.2 years in general, 9.4 ± 1.1 years in urban and suburban areas (counties) respectively. 9.4±1.1 and 9.6±1.2 years; earlier in urban areas than in suburban areas (counties). In contrast, the time of menarche for girls in Beijing was 14.16, 12.62, 12.50, 12.14, and 11.90 years in 1962, 1985, 1991, 2000, and 2004, respectively. The survey of girls in provincial capitals showed that girls in the northwestern region, where the economy and living standards are backward, had their first menstruation later than girls in economically developed areas. The age definition for the development of sexual characteristics before the age of 8 years in the diagnostic criteria for female precocious puberty was derived from the data of pubertal development in the 1960s. Nearly half a century later, the definition of the diagnostic age for precocious puberty has been challenged. A 1997 study in the United States showed that the age of breast development was (8.87 ± 1.93) years for African-American girls and (9.96 ± 1.82) years for white girls. Extrapolating from this data, using -2SD as the diagnostic criterion, the diagnostic criterion for precocious puberty should be 5 years for African American girls and 6 years for white girls. However, everyone still follows the previous diagnostic criteria. There is a lack of accurate data on the prevalence of central precocious puberty. Since cases of female precocious puberty are predominantly central precocious puberty, data on the incidence and trends of female precocious puberty can reflect the incidence of central precocious puberty. In Denmark, a survey of the registered population during 1993-2001 showed a prevalence of precocious puberty of 0.2% (20-23 per 10,000 population). The limitation of this data is that it may include partial precocious puberty. This is the first nationwide epidemiological study of precocious puberty to date. 1981 US report estimated the prevalence of precocious puberty to be 1:5000-10,000. data from Danish study showed 4-5 cases per year in Denmark in 1961 and 50-70 cases per year between 1993-2001. In China, there are not many data on the investigation of the incidence of precocious puberty, especially idiopathic precocious puberty, and most of the research studies only stop at the studies conducted on breast development. According to the age definition of precocious puberty, we can reflect the incidence of precocious puberty according to the data of pubertal development survey. The incidence of early menarche was 0.79% if the age of <10 years was used as the diagnostic threshold, and 0.12% if the age of <9 years was used as the threshold. 2002 data from a study in Shanghai showed that the incidence of early breast development before the age of 8 years was 2.4% in suburban areas and 1.0% in urban areas. A survey on the development of secondary sexual characteristics and the age of menarche in girls in nine major cities in China showed that more than 10% of girls showed breast development before the age of 8 years, and 1.65% of girls in the lO years group showed menarche.