Patients with pain in the posterior side of the armpit, the common clinical causes are mainly the following cases. First, local hair follicles on the posterior side of the axilla accompanied by acute infection can form sebaceous cysts and infections, inducing local redness, swelling and pain. It can be applied externally by applying Ruyi Jinhuang cream or vital iodine gauze, while taking oral amoxicillin to promote faster absorption and remission of local inflammation. If local abscesses are formed, abscesses need to be drained under anesthesia in order to improve pain. Second, patients with acute necrotizing pancreatitis may have severe abdominal infection caused by a large amount of pancreatic enzymes leaking into the abdominal cavity, resulting in radiating pain in the posterior side of the axilla. The nature of the lesion can be clarified by enhanced CT examination of the pancreas, and anti-infection, inhibition of pancreatic enzyme secretion, massive rehydration, and dilution of toxins in the body can be given as soon as possible. If necessary, timely surgery can be performed to remove the necrotic tissue in the abdominal cavity and enhance drainage, and some patients can often achieve certain treatment results.