Acute mastitis is an acute purulent infection of the mammary gland, an inflammation of the connective tissue in and around the ducts of the mammary gland, which occurs in postpartum lactating women, especially in primiparous women. It is a very good idea to have a good understanding of the situation. The diagnosis is based on the following: 1. History Acute inflammatory manifestations such as redness, swelling, heat and pain in the breast; mostly in lactating women, often occurring 3-4 weeks after delivery; also in non-lactating women. 2.Signs Acute inflammatory manifestations such as redness, swelling, heat and pain in the affected breast, often accompanied by enlarged axillary lymph nodes and pressure pain, etc., often accompanied by chills, high fever, rapid pulse and other signs of systemic toxicity with the development of inflammation. 3.Laboratory examination The white blood cell count is significantly increased. 4.Imaging examination Ultrasound suggests inflammatory infiltration, single or multiple pus cavity formation.