As a new fabrication technique based on rapid prototyping, vacuum casting process can be especially used in the stage of products development. In this paper, a self-designed and made silicone mould was used to study process of vacuum casting panel part. ProCAST software was adopted to analyze the melt flowing behavior and effects of processing parameters. The key vacuum casting parameters, such as mould temperature, melt temperature, degree of vacuum and coefficient of heat transfer, on the effects of the filling rate of polymer melt were emphasized to be numerical studied. The results indicate that mould temperature and coefficient of heat transfer have the most important influence on quality of the formed panel.