The other parts of data are from living experiences or scholars’ research.
This paper starts with the definition and practice use of relevance. Firstly, it dissertates the framework of Relevance Theory, and defines its functions in language. Secondly, this paper uses Case Analysis and Documentary Analysis as tools, choosing the Business Communication as its specified object, clearing the characteristics and forming process of misunderstanding in Business Communication. With the help of document, resources and examples can be used to explain the misunderstanding in Business Communication systematically.

2  Relevance Theory
Relevance Theory is put up by two famous linguists, Sperber and Wilson, in their resounding book Relevance: Communication and Cognition in 1986. It considers communication is an ostensive-inferential process. Speaker will make inference based on hearer’s cognition ability and communicative resource, and chooses ostensive stimulus according to his inference. While hearer will receives speaker’s ostensive information and makes his inference, in order to find out real contextual effect and recognize speaker’s intention. A successful communication is based on a best cognition mode----Relevance. Hence, from Relevance Theory, "relevance" means whatever allows the most new information to be transmitted in that context on the basis of the least amount of effort required to convey it. Relevance Theory explains a successful communication’s process, and relevance can be a important standard of it.

2.1 contextual effect/processing effort
From the information above, it is known that relevance can judge whether a communication is successful or not. But, a standard shouldn’t merely be a simple definition. It should have clear explanation and legal formation. In a communication, inference is the most important element. Hence, inference can be a direction access to achieve the goal. According to Relevance Theory, an inference cannot be simply judged right or wrong when it lacks certain context. Sperber and Wilson consider that only an inference in a certain context functions certain contextual effect, this inference will have its relevance in this context. Contextual effect is relation between given information and context, which is important to describe relevance.
For example: （in a business conference）
A: 100,000dollars will be required to make this deal, sir.
B: Oh, well, money doesn’t grow on trees.
From this turn, B’s saying seems nonsense. But when explained by relevance, it makes sense. In this context, A’s words convey this information: I need 100,000dollars to accomplish my work. B indeed receives this information and makes it clear, but according to his financial budget and ostensive stimulus given before, he infers that this sum of money is too large to afford. He doesn’t want to break harmonious atmosphere, while he wants to inform A that 100,000dollars for B is a joke. Through B’s answer is strange, but contextual effect has no difference with “sorry, I can’t pay that much.”
Contextual effect is an important method to define relevance in that contextual effect is produced by psychological activity. Psychological activity includes hearer’s processing effect----effect on dealing with speaker’s ostensive stimulus and time spending. Processing effect is a negative element to define relevance, turning out to be inverse ratio with relevance. Hence, we can make a chart given below:
Relevance
   Contextual effect
Relevance
 Processing effect

In Sperber and Wilson’s “content condition”, relevance is defined as below:
(a) Other things being equal, an assumption with greater contextual effects is more relevant.
(b) Other things being equal, an assumption requiring a smaller processing effort is more relevant. (S&W，1995) 关联理论维度之交流环境中的误解探析(3):http://www.youerw.com/yingyu/lunwen_8317.html