Nipple inversion refers to the inversion of the nipple, which may be caused by congenital factors such as underdevelopment and lack of tissue support, or by acquired factors such as inflammation and tumor. 1. Congenital factors: Research shows that in most cases, nipple inversion is caused by congenital factors, such as mammary smooth muscle dysplasia, lack of support of nipple tissue, short mammary ducts, and fibrotic contracture of breast tissue. 2. Acquired factors: However, there are a few cases of nipple inversion caused by acquired factors, which are mostly seen in breast duct dilatation, periampullary inflammation, breast cancer and other diseases in clinic. Secondly, the common triggering factors of nipple inversion are breast surgery, trauma, breastfeeding, ageing and so on. This disease is mainly manifested as nipple depression on the surface of the areola, the presence of a small amount of fibrosis, and may be accompanied by eczema. Patients need to take care to keep the area clean and properly traction the nipple. Usually, most of the inverted nipples can be corrected after reasonable treatment, so patients are advised to go to the hospital in time and strengthen their daily life management.