With the rapid development, maturation and promotion of cochlear implant technology, scholars generally agree that cochlear implants are not only needed for patients with severe or profound sensorineural deafness in both ears, but also for the following cases: (1) Patients with bilateral low-frequency residual hearing and severe or profound sensorineural deafness in the middle and high frequencies, which can be effectively protected by soft electrodes and (2) For patients with unilateral severe or profound sensorineural deafness, especially those with severe tinnitus in the hearing impaired side, cochlear implantation will not only provide better sound perception and source localization, but also improve tinnitus to varying degrees; (3) Patients who cannot achieve good speech recognition even with well-equipped hearing aids will be considered for cochlear implantation. (3) Patients with severe sensorineural deafness who cannot achieve good speech recognition, with monosyllabic words at 70 dB SPL, are only 30-40%. It is an objective phenomenon that if one cannot have a normal telephone conversation with a stranger with hearing aids, cochlear implant surgery should also be considered. (4) Many patients with cochlear malformations, especially cochlear malformations, have good results with cochlear implants, such as Large Vestibular Aquduct Syndrome (LVAS) and Mondini inner ear malformation. However, cochlear implantation should be performed with caution in cases of severe inner ear dysplasia, such as cochlear malformation in which the vestibule and cochlea are fused into a single spherical cavity, or cystic cochlear malformation in which the cochlea is separated from the vestibule but the cochlea is sac-like. This is because, when the inner ear is severely malformed, there are relatively few auditory nerves available for electrode stimulation, and therefore, severe malformation of the cochlea can affect the hearing outcome after surgery.