A small hole behind the ear clinically refers to an infection of the sebaceous gland cyst behind the ear, which is also known as a powdery infection. This disease may be caused by the patient’s fondness for spicy and stimulating foods, frequent late nights, fire, smoking and drinking, and unclean and unhygienic localization behind the ear. Some patients are obese and may have a relationship with factors such as greasy skin. It is mainly caused by the blocked secretion of sebaceous glands behind the ear, and the non-stop retention and accumulation of secretions lead to the expansion of the cystic skin and the formation of cysts. Once the cyst is locally accompanied by bacterial infection it can form an abscess, and the abscess breaks down and pus can form a small hole and other related manifestations. In the early stage, antibiotics can be applied for anti-inflammatory treatment, and local antibiotic ointment can be applied for treatment. Once the local abscess breaks down, local debridement and drainage treatment can be done, and the best clinical treatment is to do scraping surgery of the cyst and cystic dermis, and then to perform para-suture.