Abstract: Cochlear implant(CI) is an electronic device that provides partial hearing to severely to profoundly hearing-impaired people.The signal processing strategy is one of the key technologies for CI.The strategy determines the characteristic of the output signal from the electrode of the implant.The mechanism of electric hearing is introduced firstly.Then,the research progress of the CI signal processing strategy in the last 4 decades is investigated based on the auditory perception model and presented in chronological order.Finally,the research direction on the strategy is prospected.