The purpose of this study is to investigate on the properties of the sentence structure and the constituent of Korean children`s speeches before 24 months. If children`s sentences are generalized down to sentence structure with the exception of constituents, language acquisition competence of childhood isn`t analyzed properly, because children`s utterance include a part of all sentence. From this point of view, we analyzed the sentence structure and the constituent at the same time. In children`s speech, the construction of a sentence is divided into three classes; the modification, predication and parallel construction. Of the modification constructions, the nominal phrase is acquired prior to the verbal phrase. The predication construction is divided into five types; the copula sentence(지정사 구문), the existence verb sentence(존재사 구문), the transitive verb sentence(타동사 구문), the intransitive verb sentence(자동사 구문), the adjective sentence(형용사 구문). We analyzed each construction and the constituent in detail. And the only one example represented in parrel construction is `엄마하고 아빠하고`.