Abstract:  This paper aims to analyze the application of politeness principles in the writing of business English letters through the studies of business letter examples, and study how to use politeness strategies to improve the ability and quality of English business letter writing. Relevant politeness principles in pragmatics are used to study the language selection and the important points of letter writing in different cultural contexts, to achieve the purpose of communication in the cross-cultural communication.

Key words: Business English letter, application, politeness principles

摘要：   本文通过对商务信函实例的研究，分析礼貌原则在商务英语信函写作中的应用。文章运用语用学中的相关礼貌原则从言语选择、辞藻筛选以及在不同文化背景下信函写作的注意点等方面出发，研究如何使用礼貌策略提高商务英语信函写作的能力与质量，以达到在跨文化交际中的交往的目的。

关键词： 英语信函；应用；礼貌原则