Indications for cochlear implant surgery: Bilateral severe or very severe sensorineural deafness. Hearing loss of ≥70 dB on pure tone audiometry; auditory brainstem evoked potentials of ≥100 dB. No contraindications to surgery on medical examination, basically normal cochlear development, no post cochlear lesions, normal mental, intellectual and behavioral development. The patient or parents have a correct understanding of the cochlear implant and appropriate expectations. Contraindications to cochlear implantation: 1. Cochlear and auditory nerve factors: The relative contraindications to cochlear implantation surgery are considered to be the complete absence of the cochlea and severe narrowing of the internal auditory canal from an imaging perspective. The cochlear implantation is generally contraindicated when the internal auditory canal is less than 2 mm because of the lack of auditory nerve and vestibular nerve in the internal auditory canal. 2. Middle ear infection: In patients with purulent otitis media, the electrode implantation will bring the infection into the inner ear. If you want to implant a cochlear implant, the head should have the otitis media completely removed. 3. Cochlear fractures: Cochlear fractures are likely to damage the auditory nerve and make cochlear implantation ineffective. 4.Patients with mental illness: Electrical stimulation may stimulate the cerebral cortex, so mental illness is a contraindication to cochlear implantation surgery. 5. Contraindications to other routine surgical procedures are also not considered for cochlear implantation.