Mammary gland hyperplasia, also known as mammary gland structural dysplasia, etc., is a common breast disease among women, characterized mainly by hyperplasia of the constituent parts of the breast, with a certain degree of abnormality in structure, quantity and histomorphology, mainly related to ovarian dysfunction. Breast cancer is a common malignant tumor in women, which is a new organism formed by the abnormal proliferation of cells in the body, and the main relevant factor is estrogen. The differences between the two are as follows: (1) Different nature of disease: breast hyperplasia is a physiological lesion, neither inflammation nor tumor; while breast cancer is an organic lesion, which is the result of serious disorder of cell growth regulation caused by the action of various tumorigenic factors, and is a malignant tumor. （Breast cancer is a malignant tumor that can endanger human life and can recur after surgery, but it can be cured clinically if detected and diagnosed early. (3) Different symptoms: Although breast hyperplasia has scattered lamellar tissue in the breast, one or both breasts will be swollen and painful, but the pain will be reduced or disappeared after menstruation. With the development of breast cancer, most of the painless lumps will appear. As the lumps increase in size, “dimple sign” and “orange peel-like changes” will appear, and the nipples will overflow with blood, retraction and erosion. (4) Different treatment methods: As breast enlargement is a benign disease, most of them do not need treatment, but mainly need attention in daily life, and can be treated with medication if the pain is obvious. Breast cancer, on the other hand, is a comprehensive treatment based on different classifications, mainly surgery. Although there is a clear difference between breast enlargement and breast cancer, there is a possibility of cancer hidden in the thickened glands of a few patients. Therefore, it is necessary to be vigilant in daily life.