Topic: brief introduction on the role of interaction in early second language acquisitionA. IntroductionSeveral hypotheses have been put forward by scholars to study second language acquisition (SLA) in order to promote understanding of the language learning process. According to Beller (2008), most hypotheses focus on the subsequent SLA, such as the behavioristically oriented “contrastive hypothesis”, the nativist oriented “identity hypothesis”, as well as the crosslinguistic hypothesis, while few studies have lent pay attention to the SLA of bilingual preschool children. With the increase in immigrants and the importance of ASL perceived by bilingual parents, their children tend to learn the second language (L2) early along with the first language (L1). As a limitation of cognition and maturity, children learn language primarily from the stimulation of the external environment created by their parents, educators, and peers. The quality and quantity of language input, which functions as stimulation, interacting with people around children, has a positive influence on children's language learning (Bradley and Caldwell 1976; Clarke-Stewart 1973; McCartney 1984; and NICHD 2000). Therefore, it is useful for both parents and teachers to know how interaction can improve children's English proficiency. Therefore, the purpose of this article is to introduce the role of interaction in early L2 development and the implications of children's interaction in L2 development. instruction. This article will introduce the topic from three aspects. In the first part, the literature review will include interaction with parents, teachers and peers respectively. The second part concerns the implications of linguistic competence int...... half of the document ......and pre-school children. Previous research shows that through interaction with parents, especially mothers, teachers and peers, L2 grammar, semantics and vocabulary were improved to a certain extent. Given the positive effect of interaction on language proficiency, parents and teachers should apply interaction skills in teaching L2 to young children. Parents should pay attention to the use of open-ended questions and take different positions to stimulate communication with children, while teachers should focus on creating a social interaction context to encourage children's verbal interaction with teachers and their peers . However, due to the author's limitations, the importance and methods of interaction may not be fully introduced. The present findings may also provide some advice to parents and teachers.