Abstract：Business letters play an important role in business communication. Its effective use has a close bearing on the whole transaction. Though “correctness” and “clearness” are the principles of writing business letters, under some circumstances the addresser may employ the vague language to convey the information to the addressee, so that it can finally reach to the specific communicative intentions. 

Based on various relevant theories, especially Joanna Channell’ s (1994) research results, twenty pieces of business letters are chosen to analyze the situations and pragmatic functions of vague language in business communication. The dissertation primary explores the six situations and six pragmatic functions from the positive aspect of vagueness.

Key Words: vague language; business letters; situations; pragmatic functions

中文摘要：商务信函在商务交际中发挥着重要的作用，它的有效运用密切关系到整个交易的顺利完成。虽然“准确”和“清楚”为商务信函写作的基本准则，然而在某些情形下，写信者需要运用模糊语言向收信者传达信息，以达到特定的交际目的。 

本篇论文在相关模糊理论的基础上，尤其Joanna Channell（1994）的研究成果，结合20则商务信函来分析商务信函交际的运用情景以及语用功能。从模糊语言的积极方面出发，本篇论文主要探索了模糊语言在商务信函运用中的6种情景及所产生的6种语用功能。

关键词：模糊语；商务信函；情景；语用功能