The present study uses three self-paced reading experiments （word-by-word presentation, portion-by-portion experiment and sentence-by-sentence presentation） in order to explore if Lexical Bundles, the highly recurring word sequences, can be stored and accessed as a whole during language processing. The subjects include native English speakers and second language （L2） learners of high proficiency level and low proficiency level. The results show that the native speakers and L2 learners of high proficiency level possess a similar processing mechanism in that they can process the sentences with lexical bundles faster than their non-lexical bundles counterparts. L2 learners of low proficiency level, however, do not possess that mechanism. The author also relates the results to the study of L2 learners’ implicit lexical knowledge. Compared with the explicit knowledge, the implicit knowledge plays more important role in language processing. The unique role of lexical bundles in language processing makes it imperative to teach L2 learners those high frequency lexical bundles.