Abstract: Idiom is one type of figurative language. Idioms’ literal meaning can be accessed when its syntax is processed as well as its figurative meaning can be accessed when its semantics is processed. The two processes are contradictory, however, which result in the promotion of viewpoints such as non-composition, composition and relevance theory. Those who hold the non-compositional opinion propose that figurative meaning is accessed immediately in processing idioms while morpheme plays an important role in processing idioms according to compositional viewpoint. Relevance theory assumes that the purpose of processing idioms is to try to find out the maximum semantic relevance between morpheme and lexicon and the maximum efficiency of exchanging information in pragmatics. A great number of researches show that neither of the viewpoints and theory mentioned above can be used individually to explain how idioms are processed, thus idiomatical phrases processing relies on the multiple psychological mechanisms.

Key words: idiom, non-compositional viewpoint, compositional viewpoint, relevance theory, consideration