Abstract: Bilingual individuals needed effective mechanisms to switch their different languages in everyday life, which was called language switching. The present review focused on three fundamental issues in the processing of the non-target language in language switching: 1) whether the non-target language was activated when bilinguals intended to use the target language? 2) If the non-target language was activated, then at what level did this activation occur, at the conceptual level or the lexical level? and 3) If the non-target language was activated, then what influence would it exert on the processing of the target language? Based on these three questions, some studies on language switching in language production and language comprehension were reviewed. Finally, the prospects for the future studies were showed.

Key words: bilingualism, language switching, language production, language comprehension