According to statistics, nipple discharge as the first symptom of medical consultation accounts for 3% to 14% of breast diseases, the incidence of which is second only to breast lumps and breast pain. Most of the nipple discharge is related to the following breast diseases: (1) Dilatation of mammary ducts: some patients with this disease have nipple discharge as the first symptom in the early morning. The color of the overflow is mostly brown, and a few of them are bloody; the laboratory examination of the overflow shows that there are a lot of plasma cells and lymphocytes without cancer cells. The disease is most common in non-lactating or menopausal women over 40 years of age. There is skin adhesion in the areola area where the overflow occurs, and the diameter is often less than 3 centimeters, and the lymph nodes in the axilla on the same side may be enlarged, soft and tender, and if complicated by infections, the lumps will have the inflammatory manifestations of redness, swelling, heat and pain locally. (2) Intra-papillary papilloma: this disease is common in 40-50 years old people, 75% of the tumor occurs in the adjacent nipple part, the tumor is very small, with tip and villi, and there are a lot of thin-walled blood vessels, so it is easy to bleed. Cancer cells can be found in the overflow. Sometimes, if the patient touches the breast carefully, a cherry-sized lump can be found under the areola, which is soft, smooth and movable. (3) Breast cystic hyperplasia: it is mostly seen in women of childbearing age. Some patients have yellowish green, brown, bloody or colorless plasma-like nipple overflow, and there are no tumor cells present in the overflow in laboratory examination. There are two characteristics of this disease: first, it is manifested in breast cyclic distension and pain, which occurs or aggravates in the pre-menstrual period, which is not minded by the patients in mild cases, but can affect the work and life in severe cases. Secondly, breast lumps often occur, can be seen on one side or both sides, can also be limited to a part of the breast or scattered throughout the breast. The lumps are nodular and of different sizes, tough and not hard, with no adhesion to the skin and unclear boundaries with the surrounding tissues, and the lumps may shrink after menstruation. (4) Breast cancer: some breast cancer patients have bright red or dark red nipple discharge, sometimes produce watery discharge, colorless and transparent, occasionally viscous, leaving no traces after discharge, and cancer cells can be found in the discharge. 45-49 years old and 60-64 years old are the two peaks of this disease. The onset of the disease is slow, and patients may find breast lumps unintentionally, mostly located in the inner upper quadrant or outer upper quadrant, painless and gradually enlarged. In advanced stages, the lesions show orange peel-like skin changes and satellite nodules. The axillary lymph nodes are enlarged, hard, and progress with the disease.