Abstract: This paper, based on Visual Grammar, attempts to explore the realization of representational meaning, interactive meaning and compositional meaning in the posters of Harry Potter movie series, and demonstrates the connection and differences of the posters in terms of realization of the three strands of meaning.Through the analysis, some conclusions can be drawn as follows.First of all, representational meaning reflects the content of each individual poster, and displays certain plot of corresponding movie;interactive meaning construction appeals to the viewers and arouses their interests in movies;compositional meaning construction emphasizes prominent information of the posters.Secondly, representational meaning construction and compositional meaning construction demonstrate the unity of the eight posters;interactive meaning construction reveals the particularity of the posters of the first and the last two episodes, and the connection between other posters.