Mammary gland hyperplasia and breast fibroadenoma are common diseases in breast disease clinics, and breast cancer is a malignant tumor that seriously endangers women’s physical and mental health, so what are the features that can help us make differential diagnosis of these three diseases?1. Mammary gland hyperplasia is common in middle-aged women, and its cause is mainly endocrine disorders that cause excessive hyperplasia and incomplete rejuvenation of breast tissue during the menstrual cycle. The clinical manifestations are periodic unilateral or bilateral intermittent breast swelling and discomfort, obvious during premenstruation and relieved after menstruation; the pain is also sensitive to the friction of clothes when obvious; often accompanied by dysmenorrhea, menstrual disorders and menstrual tension. Small, scattered nodules or lumps of varying sizes are often found in the upper outer quadrant of the breast, with poorly defined boundaries with the surrounding tissues, mostly painful to the touch, with no adhesion to the skin or deeper tissues, and movable. In a few patients, straw-colored or brown spontaneous overflow from the nipples can be seen. The disease can be seen in any age group after puberty and before menopause, and the severity of symptoms is mostly related to exertion, emotional changes and menstrual cycle. Ultrasound examination reveals bilateral breast enlargement with thickened glandular layer and enhanced echogenicity with smooth and neat margins. The internal structure of the gland is disturbed and may be accompanied by dilated milk ducts. 2. Breast fibroadenoma is a common benign breast tumor in women, mostly found in young women, mostly in the outer upper quadrant, mostly solitary, but also multiple. Patients often have no obvious conscious symptoms, but are mostly found during physical examination or unintentionally. Breast ultrasound shows clear borders, lateral acoustic shadowing, fibrous separation and coarse calcified spots, posterior echogenic enhancement, good mobility of the nodule, and a small amount of blood flow signal can be detected inside and around the nodule. 3.Breast cancer Most often occurs in middle-aged and elderly women, with a hard, painless lump in the breast, mostly unilateral, easily adhered to the skin and surrounding tissues, fixed and unchanging, rapidly increasing in size within a short period of time. The lump is fixed and grows rapidly within a short period of time. The lump is not significantly related to menstrual cycle or emotional changes. Ultrasound of the breast showed irregular margins, crab foot-like and burr-like, with small calcified dots and diminished posterior echogenicity; the internal blood flow signal was rich. Mammography, MRI and puncture biopsy or surgical biopsy can provide a more definitive diagnosis.