AbstractObjectivesTo investigate the relationship between auditory pathway function and cochlear size in deaf children with a radiologically normal inner ear or Mondini malformation.MethodsThirty‐five deaf children without inner ear malformations (IEMs) and forty cases with Mondini malformation were included in this study. The electrically evoked auditory brainstem responses (EABRs) evoked by electrical stimulation at the round window niche (RWN) and round window membrane (RWM) were recorded during cochlear implantation (CI) surgery. The anatomical parameters of the cochlea were assessed by high‐resolution computed tomography and OTOPLAN 3‐D construction software. Correlations between EABRs and cochlear sizes were analyzed.ResultsThe EABR thresholds and/or latencies were negatively correlated with the basal cochlear diameter, cochlear width and/or cochlear duct length in both patients without IEMs and those with Mondini malformation.ConclusionThe physiological function of the peripheral auditory system depends on the anatomical structure of the cochlea to an extent. A larger cochlear size appears to be associated with better auditory conduction function. Our findings may be beneficial to selection of the proper electrode type and prediction of postoperative auditory rehabilitation.Level of EvidenceLevel 4.