Middle ear mastoid cholesteatoma is a common disease in otology. Although cholesteatoma is not a tumor, it is locally destructive and easy to recur after surgery. Its main features are; flow of foul-smelling pus, progressive hearing loss, and in severe cases, it can cause meningitis, brain abscess, sigmoid sinus thrombophlebitis, postauricular subperiosteal abscess, facial paralysis and other intracranial and extracranial complications, and even life-threatening. Once cholesteatoma formation is found, it is necessary to consult the doctor as early as possible and take therapeutic measures. The occurrence of cholesteatoma is complicated, and it can be either congenital or acquired. Congenital cholesteatomas are most common in children or adolescents, with gradual hearing loss and pus in the ear when accompanied by infection. In acquired cholesteatoma, some patients have a history of secretory otitis media, and although the symptoms of ear stuffiness improved later, the hearing was not restored, or even decreased progressively, and the eardrum was invaginated, and cholesteatoma was gradually formed. The marginal perforation of the tympanic membrane or even central perforation may lead to the formation of cholesteatoma.CT examination may show the destruction of the middle ear mastoid bone (including the auditory ossicles), and MRI examination is needed to exclude intracranial and extracranial complications if necessary.