In recent years, precocious puberty in children has caused widespread concern in society, and the number of infants and children suffering from premature breast development is increasing,? Through the clinical follow-up of children with premature breast development within 2 years of age, we also found that some children’s breast enlargement can persist or have recurrence and finally progress to central precocious puberty. In addition to nutritional conditions and lifestyle changes, it may also be related to environmental factors. And the 2010 milk powder incident has made us pay more attention to the influence of environmental factors on the endocrine system, especially the widespread presence of endocrine disruptors. Currently, most of the studies on the correlation between environmental endocrine disruptors and precocious sexual maturation focus on children older than 3 years old, while the study of environmental endocrine disruptors and early breast development in infants and young children has not been reported in the literature at home and abroad. This paper provides a theoretical basis for early intervention in early sexual maturation in infants and young children.