Metalinguistic awareness is defined as the ability to reflect on and manipulate the structural features of language． The present paper first introduces the operational definition and the measuring tools of  metalinguistic awareness ，and talks about the transfer of  metalinguistic awareness  across  the  native  language  and  the  second  language． Then ，the  significance  of  metalin- guistic awareness in second language acquisition is justified．     Dynamic and Interactive Model is proposed at the end of the paper ， which depicts the exact influence of metalinguistic awareness in second language acquisition．        In this model ，metalinguistic aware- ness ，native language ，working memory ，naming speed ，and affective factors constitute a dynamic and organic system ，shedding influence on second language acquisition as a whole．