Pain under the left ear is clinically common in the following diseases: 1, lymphadenitis, the primary focus can be acute otitis externa, acute otitis media, or inflammatory infections of the pharynx. Generally, anti-inflammatory treatment and fluid infusion are given in this case, and the pain will gradually disappear after the inflammation is relieved.2. Inflammatory infection of the parotid gland under the ear, which is more common in children and adolescents, can be determined clearly by doing ultrasound of the parotid gland and serum amylase and other tests in the clinic.3. Inflammatory infection of the sebaceous cysts under the ear, which is also known as sebaceous cysts, which is not broken in the early stage. In this case, when there is no rupture in the early stage, anti-inflammatory treatment is needed, and once the local enlargement is very obvious or there is abscess in the local area, clinically it is usually necessary to carry out surgery, such as incision and drainage treatment.