Abstract:China has joined the World Trade Organization (WTO). Along with the increasing number of foreign business contact, foreign-related staff will deal with more commercial correspondences every day. To a certain extent, the success of a transaction depends on whether they use correct, concise and appropriate English in communication. This paper aims to take the Cooperative Principle as theoretical guidance combining with some examples to explore the usage of the Cooperative Principles in business letters. 

　　　The paper is divided into four parts. The first part is an introduction to the theory of the Cooperative Principle and the functions of business letters. In the second part, the writer analyses the Cooperative Principle in business letters. In the third part, the writer analyses the violation of the Cooperative Principle in business letters. The last part is the conclusion.

Key Words: cooperative principle；business letters; violation

摘要:中国已加入世界贸易组织（WTO），随着对外业务往来的逐渐频繁，涉外业务人员每天将处理更多的商务信函。在处理这些商务信函时，如何用正确简洁得体的英语与客户进行交际关系到交易的成败。本论文旨在以商务信函为切入点，以合作原则为理论指导，结合实例进行分析，以此说明格赖斯合作原则在商务信函中的体现。

　　　论文分四大部分。论文开头简短介绍了合作原则理论和商务信函的功能。第二部分分析商务信函中的合作原则。第三部分探究商务信函中对合作原则的违反。第四部分得出结论。

关键词：合作原则；商务信函；违反