Breast pain can be caused by the following reasons: Firstly, breast pain occurs in menstruating women, because the estrogen level is constantly changing, before and during menstruation, due to the stimulating effect of high estrogen level will produce breast enlargement causing tissue edema and pain. Secondly, breast tumor will produce local skin changes such as unevenness, color change, rupture or secretion, and breast tissue changes, both malignant and benign. Thirdly, there are two kinds of mastitis, one is caused by bacterial infection and the other is caused by a large amount of milk accumulation in the mammary gland due to failure to suckle and breastfeed in time. In all these cases, it is necessary to go to the breast surgery department to find out the specific cause and make a diagnosis.