In order to achieve an adequate understanding of communicative intention,we should not only understand the surface meaning of the utterance,but also of the intended meaning.In some immnces,the surface meaning and intended meaning match.It is easv for us to understand the utterance.However,in many cases,the intended meaning differs form surface meaning,the intended meaning is a case of indirect meaning.Searle defined this case as indirect speech act.This paper explains indirect speech act through the disagrcements between forms of basic types of English sentences and their basic illocutionary functions.The aim of the paper iS to let the leamer communicate effectively and appropriately by using language,so teachers should pay attention to language illocutionary function and learners'communicative competence.