Abstract:With the change of the trade environment after China joined in the WTO, our country is integrated into a more complicated international environment. For the fierce competition, staffs are required to use English on more occasions. Among the several communication tools, business letter remains an indispensable part of business communication. A well written letter can mean advancement for the writer’s career, profit for the writer’s company and satisfaction for the writer’s clients. It is of great use for us in enhancing mutual comprehension and promoting trade. 

　　　This dissertation mainly discusses the general structure and basic skills of business letter writing, some basic types of business letter by using the eight C’s techniques, and the eight C’s criteria for effective communication,. It is hoped that the findings of this dissertation will provide a further insight into the more effective and particle ways of modern business letter writing.

Key words: business letter; effective writing; eight C’s principle

中文摘要:随着加入世贸组织之后贸易环境的变化，中国进入了一个更复杂的国际经济环境。激烈的竞争要求公司职员在更多的场合使用英语。在商务往来中，商务英语信函在众多通讯方式中保持着着重要角色。一封成功的的商务信函意味着你的事业的发展，你的公司利益的提升，客户的满意，它是增进理解和扩大贸易的重要手段。

本文主要讨论商务信函中的一般知识和基本技巧，一些基本商务信函中的运用, 以及商务信函写作中的“8C”原则。希望本文的研究结果能为现代商务信函的写作提供更有效，更实用的方法。

关键词：商务信函；有效写作；8 C 原则