Internal mixers are widely used in rubber compounding in tire manufacturing process. This paper is a review of rubber mixing analysis in internal mixers and consists of two parts. First one is a literature review of rubber mixing simulation in internal mixers. Literatures were summarized in four view points; fully-filled simulation, partially-filled simulation, evaluation method and comparison with experimental results. Second part shows the examples of the authors' partially-filled mixing simulation and its visualization results by using expanded coordinate and particles as fluid.