There are more ways of research and broader points of view as to Japanese expression of inference in recent days.However,subtle differences exist between the various expressions of inference.This paper focuses on the main causes of Japanese ambiguity and the related way of expression——inference.With the comparison,induction and summary of the usage of the inferring expressions such as らしい、ようだ、みたいだ,this paper aims at helping students to solve the problem of misusing expressions of inference.