As the antithesis of politeness studies, the study of impoliteness becomes a hot spot in pragmatics. In this paper, Bousfield's impoliteness theory is used as an analytical foundation to study the impolite expressions of dialogue in the classic fantasy film Harry Potter and the Sorcerer's Stone. This paper focuses on the following two research questions: 1, how direct and indirect impolite discourses are distributed in movie dialogues; 2, what are the prominent forms of the two discourses. Meanwhile, the author further analyzes the different characteristics of the film characters through the film dialogue in the impolite words.