Politeness is a necessary quality and a universal phenomenon in the civilized society.When communicating with others,Politeness Principle should be used to restrict behavior.However,in the business world,Politeness Principle makes sure the communication between two parties proceed successfully.This paper aims to examine the politeness strategies used in business letter and to illustrate the importance of politeness principle in business English writing. Politeness is a necessary quality and a universal phenomenon in the civilized society .When communicating with others ,When the common law in the civilized society.When communicating with others, Politeness Principle makes sure the communication between two parties proceed successfully.This paper aims to be used to restrict behavior. to examine the politeness strategies used in business letter and to illustrate the importance of politeness principle in business English writing.