This article is devoted to the study of two children aged from 2 years and 6 months old to 3 years and 10 months old, who are confronted with the parallel acquisition of the Korean language and the French second language after the installation of their families in France. The corpus analysis obtained throughout this study permit us to clarify the specific role of the prosodic realisation during this period between 3 ;1 and 3 ;2 years old. A period when two distincts types of two elements utterances (each from his own. prosodic system, either Koean the other French) are established. In fact, this capacity of prosodic differenciation is based on the knowledge of pragmatic conditions of language interaction. It is a matter of taking the interlocutors and the situation into account. This language choice according to interlocutors must also allow children to differenciate two lexicons according to their needs. We can see how a child, at the time of language choice and being submit to context needs, gives importance to the French language at the dominant language. This adjustement of pragmatic differenciation in favour of one language takes place between 3 ;7 and 3 ;9 years old. The same tendancy is found during the lexical choice, when the presence is more and more marked by French words in the Korean utterances which happens between 3 ;8 and 3 ;10 years old respectively. Owing to the study of the installation of French dominant language, we can see that pragmatic diffrenciation comes before lexical differenciation with one month interval. This work would be permit to observe how in the early bilingualism Korean-French the capacity to diffrenciate languages appears first from prosodicpragmatic mastery and then lexical mastery.