Nipple discharge is a not so common but important symptom of breast disease. 3 to 14% of all visits to the doctor with nipple discharge as the primary symptom are for breast disease, second only to breast lumps and breast pain. Generally speaking, nipple discharge occurs in breast hyperplasia, intraductal papilloma, breast inflammation, ductal dilatation or breast cancer. According to statistics, about 5-10% of breast cancers are associated with nipple discharge, but only 1% of them have nipple discharge as the only symptom. Nipple discharge from breast cancer mainly occurs in women over 50 years of age who have a single ductal blood discharge from the nipple, while the majority of nipple discharge is still caused by benign disorders of the breast. In the past, screening of nipple discharge was mainly done by smear cytology and mammography, while surgical biopsy is still the only means to obtain a definitive diagnosis. Breast ductal endoscopy is a new method developed since the 1990s to examine lesions in the breast ducts. It is performed by inserting a 0.6mm or 0.75mm inner diameter endoscope through the opening of the overflowing duct and probing into the end of the duct through the endoscopic display while observing the situation inside the duct, as far as the fifth or sixth level of the milk duct branch. The entire procedure takes about 10 to 15 minutes without the need for local anesthesia and without any pain or discomfort to the patient. The images observed can be recorded by video or photographic recording. The endoscopic examination of breast ducts can clearly observe the condition of breast duct walls and ductal secretions, and describe the color, size, shape, and smoothness of new organisms, if any. Ductal carcinoma, intraductal papilloma, and ductal inflammation each have their own characteristic endoscopic manifestations of the ducts, and thus can be diagnosed accordingly. Another role of endoscopy is to mark the surface skin of the lesions found, thus providing accurate localization for surgical biopsy. In addition, a biopsy of the lesion can be performed under endoscopic guidance to obtain a pathologic confirmation. In general, breast ductoscopy can achieve the following objectives: 1. It solves the problem that lesions in the breast duct can only be diagnosed indirectly but not visually, opens up a new direct diagnostic method for the characterization of lesions in the breast duct, refines the indications for surgery, and reduces unnecessary surgery. 2. It solves the problem of precise preoperative localization of lesions in the breast duct, and reduces the scope of surgery. 3. With the help of breast ductoscopy, it is possible to perform With the help of breast ductoscopy, we can collect abscessed cells for cytological examination of breast cancer and also perform microscopic biopsy with the help of biopsy instruments.4. Under the microscope, we can perform milk duct irrigation to treat inflammation in the milk ducts, accumulation of obstructive inflammation in the milk and some breast hyperplasia, etc., and obtain remarkable efficacy.5. With the help of breast ductoscopy, we can carry out some minimally invasive treatment and minimally invasive surgery.