Breast shrinkage can be divided into three cases: first, when after breastfeeding, due to milk emptying breast tissue function, resulting in breast shrinkage, often a normal physiological phenomenon, later active exercise and reasonable diet can be restored. Second, endocrine hormone disorders, because the proliferation of breast tissue depends mainly on estrogen and progesterone, when estrogen levels decline, it will cause the degeneration of breast tissue, and then the phenomenon of breast shrinkage, at this time should go to the endocrinology department, to clarify the causes of endocrine hormone disorders and active treatment. Third, breast atrophy, common in elderly female patients, manifested as physiological atrophy of breast tissue and breast fat tissue, is a normal phenomenon and can not be specially treated. In conclusion, there are various causes of breast shrinkage, most of which are normal physiological changes and can be treated without too much panic.