By definition, the onset of breast development at the age of 8 is not considered precocious puberty. It can also be caused by genetic, nutritional, endocrine and other influences. Precocious puberty refers to the appearance of secondary sexual characteristics (e.g. breast enlargement) before the age of 8 for girls and 9 for boys. Genetic, nutritional, endocrine, environmental and other factors can affect the early development and size of breasts. Breast development in some women is determined by genetics. Some fried foods and puffed foods can lead to endocrine disorders and cause early development of female breasts. Breast development in eight-year-old girls may be a physiological phenomenon or a pathological phenomenon, and it is recommended to consult a doctor in time. In daily life, we should develop good habits, rational arrangement of diet, nutritional balance and comprehensive. Appropriate more exercise, maintain a normal weight.