Acute mastitis is a purulent infection of the breast caused by the invasion of bacteria into the breast. It often occurs in women who have not yet reached the full term after childbirth, and is especially common in first-time mothers. It is called “canker sore” in Chinese medicine. Acute mastitis during lactation often has a history of nipple cracking and milk accumulation. It is characterized by redness, swelling, heat and pain in the breast and poor milk secretion, and is accompanied by fever and other systemic symptoms. The treatment of acute mastitis by TCM breast surgery is very unique and has good efficacy. The key is early detection and early treatment. In the early stage of breast lumps and milk discharges, we can use Chinese medicine to clear the liver and heat, and apply Chinese herbal creams externally to clear heat and detoxify the lumps and swellings, which are effective in preventing the formation of canker sores.