Ⅰ.Introduction:Cognitive linguistics is a linguistic model developed by Ronald W.Langacker.Its main goal is to express the semiotic function of language,namely to allow the symbolization of conceptualization by means of phonological sequences.It is subjective,anthropocentric and reflects dominant cultural concerns and culture-specific models of interaction,as well as features of the world as such.The study of metaphorical expressions has played a central role in the development of Cognitive Linguistics.Since Aristotle,metaphor has been constantly analyzed.Different from the previous study,the cognitive linguistists assume that metaphor means“a crossdomain mapping”in the conceptual system(Lan Chun;2003).The cognitive approach reveals the mechanism of metaphor more efficiently and this paper will adopt the cognitive approach.