By watching the effects of cochlear implants in the children with cochlear nerve defects, to evaluate the relationship and efficiency of HRCT AND MRI in diagnostic for cochlear nerve defects.The imaging dates and the post-operative effects of the 10 cochlear nerve defect patients were retrospectively analyzed.Three patients with bilateral IAC stenosis by HRCT and cochlear nerve defects by MRI but no other abnormal. Seven other patients showed normal IAC by HRCT including 1 showed type IP- I plus vestibular semi circular canal dysplasia. These 7 patients MRI showed 3 bilateral cochlear nerve absent and 4 bilateral cochlear nerve dysplasia. Ten cases of children after 12-32 month follow-up, 3 patients began speaking simple language, whose MAIS scale, CAP and SIR scores improved. One case just began speaking but pronunciation vague. Four cases had reactions to sounds, and can say monosyllabic words. Two cases without effects (1 CI abolished). Compared with other patients with normal cochlear nerve, the effects of the 10 cases were disappointed.The effects of cochlear implant for the patients with cochlear nerve defects were poor. The preoperative MRI as sessment including oblique sagittal view for cochlear nerve is necessary. The preoperative communication with the parents telling ineffective result possibility is important.