The purpose of this study is to point that the segmental-based study on child phonological acquisition is not sufficient in accounting for the ever-changing dynamic development of child phonology and to attempt to explain child phonology in terms of syllable-based theory of phonology, one of various types of non-linear phonology which have been studied since the late 1970’s. According to Gruber’s observation, it is obvious that children perceive their own concept of syllable even at the early stage of babbling. In addition, the statistical data show that CV-type syllable is most frequently used in child phonology. These evidence seem to suffice to conclude that the CV-type syllable is the most unmarked of all four core syllable types in the sense of Clements & Keyser (1983). Starting with this observation, it is further argued that in child phonology the markedness of syllable types increase in the order of CV, CVC, VC and V.