Generally, before cochlear implantation, patients who are able to do so should have a trial period (3 to 6 months) for hearing aids. After cochlear implantation is determined, a number of detailed preoperative examinations are required, including These include a history and etiology of the ear; routine otologic examinations (to rule out otitis media and eustachian tube pathology); imaging examinations (CT and MRI) (to understand whether the middle ear and inner ear are cochlear deformities fibrosis or ossification, narrowing of the internal auditory canal or occupancy to determine the integrity of the auditory nerve and pathways); systemic status examination, as the surgery is performed under general anesthesia, so it is necessary to understand the patient’s heart, lung, liver and kidney function as well as some laboratory tests, whether they can tolerate the surgery. (2) Audiological examination. Including pure tone audiometry or sound field test, speech audiometry, ABR, multi-frequency steady state, otoacoustic emission and acoustic conduction resistance, and electrical stimulation test of the drum head. (3) Psychiatric examination: Adult patients should be mentally and psychologically healthy, have a strong demand to accept cochlear implants, be able to adhere to post-operative rehabilitation training, and be able to correctly understand the role and effects of cochlear implants. Children need the active cooperation of their parents. Absolute contraindications to surgery 1. cases with severe malformations of the inner ear, such as Michel malformation or cochlear agenesis;