Running water from the nipple is called nipple discharge, and nipple discharge is one of the common symptoms of breast disease.Nipple discharge can be categorized as self-spilling and extruding. The nature of its milky, watery, purulent, plasma or bloody, etc. The reasons for its occurrence are summarized in three. In physiological situation, the epithelium of mammary ducts has certain physiological activities, and a small amount of transparent or milky white nipple overflow can appear. 2, systemic diseases, especially some endocrine diseases, such as pituitary tumor causing hyperprolactinemia nipple discharge (breast milk – amenorrhea syndrome), often bilateral multiple ductal nipple discharge, and in a few cases of certain drugs can also be caused. The most common breast diseases that cause nipple discharge are acute inflammation of the breast, ductal dilatation of the breast, breast hyperplasia, intraductal papilloma, intraductal papillary carcinoma and breast cancer. Hemorrhagic overflow often occurs unilaterally, either by itself or by squeezing, and the overflow is bright red, light red, light brown or coffee-colored, which is mostly caused by intraductal papilloma, and can also be seen in breast cancer. If nipple discharge occurs, no matter in what way or what kind of discharge, it should be taken seriously because nipple discharge during non-lactation period is mostly a manifestation of various breast diseases. As malignant lesions are more likely to cause bloody overflow, no matter what kind of overflow should be highly alert; male patients with nipple overflow should not be taken lightly, and should go to the hospital to confirm the diagnosis as soon as possible.