To summarize the cases of temporomandibular joint herniation into external auditory canal found and treated in our hospital, to improve the understanding of oral and maxillofacial diseases and otological diseases, and to explore the potential long-term effects of local radiotherapy on temporomandibular joint function. Analyzed the causes of temporomandibular joint herniation into external auditory canal comprehensively through combining history, clinical manifestations and imaging examination. All otoscope results showed soft tissue mass in the deep anterior wall of the external auditory canal. The soft tissue mass moved inside and outside along with the opening and closing of the mouth. CT examination revealed obvious bone defects in the anterior wall of the ear canal. Delayed radiotherapy injury may be a inducing factor of temporomandibular joint herniation into external auditory canal. CT and MRI examination have guiding significance on the disease treatment selection. The specific signs found by otoscope can confirm the diagnosis.Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.