Abstract: This paper mainly introduced two theories about the mechanism of lexical access in bilingual speech production: language-unspecific selection theory and language-specific selection theory. And the question of whether or not the lexical nodes of the non-response language act as competitors to those of response language is crucial for the mechanism of lexical access in bilingual speech production. This paper mainly discussed the differences between these two theories about the crucial question. The language-unspecific selection theory states that the lexical nodes of the non-response language act as competitors to those of response language, but the language-specific selection theory does not. At last in the new trend of the mechanism of lexical access in bilingual speech production, the consistencies between these two theories on two aspects were introduced

Key words: bilingual, speech production, lexical access, language-unspecific selection, language-specific selection