In general, patients with severe cochlear deformity or cochlear absence, undeveloped or absent auditory nerve, severe mental retardation or severe mental illness are not suitable for cochlear implantation. Absolute contraindications include: ① Severe inner ear malformations, such as Micheal malformation, undeveloped or severely malformed cochlea; ② Undeveloped or absent or interrupted auditory nerve; ③ Acute purulent middle ear mastoiditis or chronic middle ear mastoiditis in the acute phase. Relative contraindications include: ① poor general condition of the whole body; ② patients with uncontrollable frequent seizures; ③ patients with severe mental, intellectual, behavioral or psychological disorders and unable to cooperate with language training.