More than three years after weaning, there will be no more milk secretion. If milk secretion is found, it may be caused by hyperprolactinemia, mammary duct dilatation, mammary duct tumor and other diseases. 1. Hyperprolactinemia: elevated serum prolactin due to various reasons, mainly manifested as menstrual disorders, amenorrhea, breast overflow and other symptoms. Clinically, this disease is mostly caused by pituitary tumor, and it should go to the hospital to do sex hormone six and brain MRI examination to clarify the cause of the disease, and be treated by medication or surgery. 2. Dilatation of mammary ducts: It may be caused by milk retention, breastfeeding obstruction, bacterial infection, etc. It manifests as nipple overflow, and may be accompanied by nipple itching, or redness, swelling and pain around the areola. 3. Mammary duct tumor: mostly related to endocrine hormone disorders, may appear painless nipple discharge, a few patients will appear breast lumps and pain and discomfort symptoms. Therefore, it is an abnormal phenomenon to secrete milk more than three years after weaning, so you should consult the doctor in time to clarify the cause and then treat it.