Language is a special tool for human communication.Blurriness is one of the basic attributes of natural language,and it is the objective reflection of language blurriness.Linguists believe that semantic blurriness exists in people’s life widely,although there is not a uniform definition.It is generally agreed that blurriness refers to the boundary or the scope of a concept that is not clear.In this paper,the author analyzes the origins of semantic blurriness from the relations between subjective and objective world,and then sums up three basic features of semantic blurriness through the combination with real life materials.Finally,from the perspective of pragmatics,the author follows the politeness principle and cooperative principle,and subsequently summarizes the pragmatic functions of semantic blurriness.Moreover,the significance of the further study of the semantic blurriness is that it helps the nature and social science to promote and develop.Besides,it also helps human beings to know themselves better.