The common clinical causes of pain behind the left ear include neuralgia, acute otitis media, otitis externa and so on. 1. Neuralgia:When the large nerve innervating the area behind the ear is in a state of viral infection, it may cause nerve damage, resulting in nerve pain. 2. Acute otitis media: this condition is often secondary to upper respiratory tract infections, and people with the disease are prone to acute otitis media. Inflammatory secretions in the ear cavity will cause stimulation of multiple nerve endings within the tympanic cavity, which will lead to ear pain in the sick people. 3. Otitis externa: some people clean the ear canal in an incorrect way, excessive use of instruments to clean the ear canal will cause damage to the skin of the external auditory canal, thus inducing otitis externa, clinical manifestations of pain in the external auditory canal. If the pain behind the left ear occurs, it is recommended to actively seek medical treatment, after a clear diagnosis and standardized diagnosis and treatment.