Abstract: Vagueness is a natural and essential property of human language, and vague language is a common phenomenon in communication. Business correspondence, a basic form of communication in business field, needs flexible command of language to achieve better communicative effects. Vague language, as a kind of efficient strategy, has been widely adopted in English business correspondence to fulfill certain communicative purposes. This study, based on the vagueness theories of Zadeh and Channell, makes a detailed analysis of the employment of vague language and its pragmatic functions in various English business correspondences. It is hoped that this research will assist addressers in writing successful business letters through appropriately employing the flexibility and strategy of vague language and finally promote the foreign trade and achieve the long term win-win goal. 

Key words: English business correspondence; vague language; pragmatic function

摘要： 模糊语是人类语言中自然的和必要的一部分，也是交流中的普通现象。商务信函，作为商务领域交流中的基本形式，需要语言的灵活指导以获取更好的交流效果。模糊语言，作为一种有效的策略，已经在商务英语信函中广泛地使用来实现某种交流目的。本文以查德和查奈尔的模糊理论为基础，详细地分析了模糊语言在各种商务英语信函中的使用及其语用功能。希望本文能帮助贸易双方在撰写英语商务信函时，恰当地运用模糊语言的灵活性、策略性，最终促进对外贸易而达到长期双赢的目的。

关键词：商务英语信函； 模糊语言； 语用功能