In vivo assessment of myelination is critical for understanding the typical and pathological brain development. Inhomogeneous magnetization transfer (ihMT) has been proposed recently and may be useful to quantify myelin contents. This study tried to evaluate performances of magnetization transfer ratio (MTR) and ihMT ratio (ihMTR) in assessing the myelination of toddler and adolescent brains. The ihMTR maps hold larger image contrasts than MTR maps. Moreover, ihMTR demonstrates larger relative changes during the period from the toddler to adolescent. Results in this study suggested that ihMTR was specific for characterizing white matter and sensitive to myelination during the brain development.