Objective To investigate the changes of electrode impedance,threshold(THR),maximum comfortable level(MCL),and dynamic range(DR),providing the basis for debugging after operation in congenital deaf children. Methods A respective study was carried out on 20 cases of congenital deaf children who were implanted with cochlear Med?EL SONATAti100. The measurements and changing ranges of electrode imped?ances,THR,MCL and dynamic range during the operation and at postoperative one month,three months,and six months were statistically analyzed. Results Electrode impedances were the lowest during the operation and the highest at one month after operation(P<0.01). The electrode imped?ance for the apical cochlear group was statistically different from that for other groups at one month(P<0.05). After three and six months,there were statistically significant differences between groups(P<0.01). THR at six months was lower than that at three months(P<0.05). MCL at three months was higher than that at one month(P<0.01). DR showed an increasing trend(P<0.05). There was no correlation of perioperative and post?operative electrode impedance with THR,MCL,and DR(P>0.05). Conclusion The electrode impedances varied due to different electrode posi?tion. The vales of THR,MCL and DR were unrelated with electrode impedance. DR was gradually increasing,MCL reached steady state earlier than THR. It is important that THR should be debugged at three months after operation and MCL should be debugged at six months.