Polite language is a very important aspect of language competence,which can smooth the social communication.This paper draws on the principle of politeness and the theory of indirect speech act before giving an analysis of polite strategies in different situations such as refusal,complaint and request,as well as the ways to produce the effect of politeness,such as fuzzy words,not-to-the-question answer and the past tense of verbs which has the effect of distance and indirectness,thus giving a new perspective to the study of politeness.