Recently the automotive industry has focused on reducing product development time to correspond with the customer's demands. Especially when quickly changed. The decreased product development time shortens the quality assurance period. It makes difficult to guarantee the quality of the products. The improved quality assurance is required so that customer's expectations are actually higher quality than in the past. Most automotive interior parts are manufactured by using plastic. It is very sensitive to focus on quality, because it is exposed to a passenger's sight. So automotive interior companies make full use of injection molding CAE in an effective ways to reduce costs and reduce elements of poor quality.This paper suggests a methodology that improves reliability for injection molding analysis in grille shapes of door trim. And it involves an experimental analysis of flow pattern in speaker grille shapes. To analyze it, use an authentic mold of speaker grilles in door trim and Mold flow software.