Abstract：China has developed a more and more closed relationship with other countries in the world since its entry into WTO. In the international trade, English letter of business relations becomes a main means in communication. Therefore, a well-written English letter is of great importance. It can not only establish a good image for the enterprise, but also facilitate the process of negotiation and goal achievement. Politeness is an inevitable element in a well-written business letter.       

　　　There are two influential theories on the research of politeness. One is the cooperative principle by American linguist and philosopher Grice, and the other is the politeness principle by British linguist G. N. Leech. These two principles have also been discussed in domestic research. However, there isn’t any deep research on politeness in English letters of business relations. The research focuses on the application of politeness principles. Through analyzing Leech’s and Grice’s theory and some important politeness dictions, comparing the difference between Chinese and Western culture, this paper tries to draw conclusions on how to utilize politeness principle in English letters of business relations.  

Key words: politeness principle; an English letter of business relations; cooperative principle

中文摘要：中国加入世界贸易组织后，中国与世界各国的关系更加紧密。在日益俱增的跨国交际中，商务英语信函成为了重要的交流手段。一封用语得当，表达有礼的商务英语信函能树立企业良好的形象，建立口碑，并且推进商务洽谈和促成商务活动成功一大重要因素。其中，礼貌是一封好的商务信函不可缺的要素。

　　　对礼貌的研究方面，美国语言哲学家格莱斯的“合作原则”和英国语言学家利奇的“礼貌原则”影响深远。国内研究也基于这两个理论展开研究。但迄今为止，却没有对礼貌原则在商务英语业务关系信函中深入研究。本文为此而之，进一步研究探讨礼貌原则在商务英语业务关系信函中的应用，通过分析格莱斯和利奇的理论和重要的礼貌用语，结合中西方文化异同，并对各种最新资料进行分析归纳，力求总结礼貌原则如何能在商务英语关系信函达到活用的效果。

关键词：礼貌原则；商务英语业务关系信函；合作原则