If there is pain behind the left ear, the following causes may be considered: 1. There may be local inflammation behind the ear, such as middle ear mastoiditis or local sebaceous cysts, resulting in infection. 2. It may be due to high tension in work or life, or poor neurotrophic factors, which may lead to nerve spasm. 3. The soft tissues or lymph nodes behind the ear have become swollen. Regardless of which of the above causes causes the pain, the first thing to do is to go to the hospital for further examination and, if necessary, anti-inflammatory and anti-swelling treatment, or even surgery can be considered. Patients should try to avoid anxiety, fire, stress, and trauma to the ear.