Nipple overflow is one of the common clinical symptoms of breast diseases. About 10% of women can be found to have nipple overflow during routine physical examination, and about 35% to 50% of them have intra-ductal papilloma and papillomatosis. In the past, the main methods of examination for nipple discharge were cytologic smear, selective mammography and ultrasound, but their diagnostic rates were not high at 50% to 80%, not intuitive and difficult to localize the lesion. A variety of benign and malignant diseases of the breast can manifest as nipple discharge, such as lobular hyperplasia, ductal dilatation, milk retention, intraductal papilloma or intraductal papillomatosis, and breast cancer (early breast cancer including intraductal carcinoma and lobular carcinoma in situ), among which intraductal papillomatosis is a pre-cancerous lesion of the breast. The screening methods for nipple discharge include exfoliative cytology, mammography, mammography, ultrasound, and ductoscopy. Mammography has now replaced mammography as the first choice for the diagnosis of the cause of nipple discharge. It is almost non-invasive, easy to operate and can diagnose lesions in the milk ducts with direct vision, and can be performed simultaneously with minimally invasive treatment.