The study was to compare the characteristics of event-related potentials (ERPs) and brain topographic maps in normal group and cochlear implant (CI) group six months after device ‘switch on’. Results showed more negative N1 component by standard and target stimuli and lower P2 amplitudes were observed for the CI group. The amplitudes of MMN component were a little smaller than those of normal group. The latency of MMN was about 13ms delayed and the latencies of N1 and P2 by standard and target stimuli were also delayed compared with normal group. The brain topographic maps may help assess the function of central auditory for CI users.