A painful lump on the tailbone is a disease caused by a perianal abscess, which is characterized by redness, swelling, hardness and pain around the anus, and can be accompanied by an increase in local and general body temperature. When the pain around the anus increases, the mass will increase progressively, and the pain is more obvious when defecating, and a hard mass can be touched by hand. In the early stage, oral antibiotics should be administered, mostly due to E. coli, and second- or third-generation cephalosporins can be given orally. If the disease progresses and liquefaction, necrosis and suppuration appear in the center of the hard mass, an abscess has formed, and after the formation of the abscess, surgery is needed to perform abscess excision or abscess radical surgery.