Relevance theory holds that the essence of communication is ratiocination; the communication process is a ratiocination process. So people should judge the communication in the perspective information handling mechanism in brain when the people are exchanging the information, it is that the brain mechanisms rather than language itself or language section process. The authors of relevance theory think that mechanism of communication worked based on people’s behavior on ratiocination in the mechanism of communication of human brain. Relevance theory has two principles: the cognitive principle and communicative principle. Cognitive principles indicate that people cognitive tend to correspond to the largest association. Communicative principle indicates that communicative behavior all should be envisaged itself has the optimal relevance. These two principles are all show the importance of early warning. (Zhao Yanchun, 1999 (3):16)

Relevance theory shows that the degree of discourse depends on effect of context and capacity of processing. The effect of context is opposite to the correlation; processing power is opposite to the association. The author considers that the processing power is equal to consume brain power in cognitive language environment，more strong the correlation, more direct the discourse .The smaller the cognition of mental, the little load of cognitive to the receivers; leading to relevance weak, the more implied words and the consumption of the brain, the greater the receiver’s cognitive load. The speaker’s use of cognitive load increase and decrease in communication is the application of communicative strategies.

2.2 Relevance Theory and Translation

Translation is viewed as an act with the characteristic of ostensive-inferential. It is one of kinds of behavior of communication, and also a process of language comprehension and language expression. What different from intralingua communication is that translation is a cross-cultural, cross-linguistic behavior or ostensive-inferential process accurately, translation behavior include two processes of ostensive-inferential, its complexity is far more than language in communication.

Communication may be considered to be a model of express - reasoning, making up for the disadvantage of the study of discourse understanding in the progress. Jiang Wanqi pided the development of relevance into three stages: the development of relevance theory growth period, mature period and revision. (Jiang Wanqi, 2002 (5):5) Growth refers to the theory of “correlation” published before developing trend, including the relevance between the shapes of ideas, unifies relevance principle, and says deepening of relevant ideas. Thought of the relevance was reflected in the correlation of growth period in Spokane and Wilson four articles published from 1979 to 1983 during the growth period. “Relevance” published in 1986 marked the maturity of relevance theory. The relevance principle is defined as: “Each expressive communicative action passes a scenario: the action itself with optimal relevance.”

Relevance theory is in an important role in guiding the study of translation, as He Ziran thinks that translation is a kind of ternary relation: the author, translator and the readers.  These three communicators interact with each other by source text and the target. Therefore, while translating, the translator has a dual function: when reading the original text, we can take this theory as a basis to know context, and by expressing the communicative behavior of the original author’s ratiocination to find out the relevance. The main task of the translator in the process of explaining the original meaning of the source text is to show the related information in the translation context which was reasoned out from the original one. That will make readers to get the biggest relevant. The two progresses all rely on the principle of relevance. Therefore, the relevance theory can seize the essence of characteristic of translation problems and have a positive effect on translation practice. (Baker Mona，2001:75-246) 关联理论视角下的《远大前程》电影字幕翻译研究(3):http://www.youerw.com/yingyu/lunwen_65403.html