Many women find breast enlargement during medical checkups and worry whether it will turn into breast cancer in the future; some other women are often troubled by nipple overflow and cannot stop worrying. Mammary gland hyperplasia is a common disease, mostly occurring in women between 30 and 50 years old. Mammary gland hyperplasia is a disorder of the normal structure of the breast. Its occurrence is related to endocrine dysfunction, reduced secretion of luteinizing hormone and relative increase of estrogen. Studies have shown that histomorphologically, simple lobular hyperplasia without ductal epithelial hyperplasia, which accounts for 70% of all breast hyperplasia, does not turn into breast cancer. Although only a small number of mammary hyperplasia will develop malignant lesions, we should still not be careless and should go to the hospital for review every 3 months. Nipple discharge is quite common, some are normal physiological phenomena, some are a manifestation of systemic diseases, and some are a reaction to local lesions of the breast. There are many diseases that occur in nipple overflow, which are summarized into three types: benign and malignant tumors; inflammation; and breast hyperplasia. Tumors account for 60%-70% of the cases, of which breast cancer accounts for 1/4. The nature of the overflow is not directly related to the cause, but the incidence of cancer is highest among bloody, plasma, and watery overflows. Most of the thin bloody overflows are cancer; mucus overflows are mostly benign lesions; while obvious bloody overflows are mostly seen in intraductal papilloma; purulent overflows are mostly due to infection. Since the incidence of breast cancer among nipple overflow increases with age, women who have symptoms of nipple overflow should rush to the hospital for treatment.