Abstract. Melt quality has a crucial influence on the subsequent processing of casting ingot and the performance of the final product. Filtration is one of the most common and important purification methods to remove inclusions in aluminum liquid during melt processing. In this paper, based on the characteristics of the filter to remove inclusions, a mathematic model is built to describe the movement and the removal of inclusions in the process, and this process is calculated with the commercial software Fluent. It was investigated in detail by using the model that the motion and removal of inclusions have different velocity and shape factor in the filtration process. Results revealed that inclusion particles with small shape factor are easy to be removed. The key point of flow velocity is found, which has critical influence on the effects of inclusion removal. The best removal efficiency can be reached when the flow velocity is at 950mm/min.