Abstract: The physical properties between matrix and reinforced phase of metal matrix composites are quite different, which leads to difficulties in sample preparation for electron microscopy. Ion polishing method is one of the effective methods to prepare electron back scattered diffraction samples of metal matrix composites. The process parameters affecting the ion polishing quality mainly include the sample protrusion and polishing time. The forming parameters of ion polishing were calculated by observing the morphology of sample with different protrusion and polishing time, combining with image processing software. The results show that the forming parameters such as polishing width, polishing depth and polishing area decrease with the increase of sample protrusion, and increase with the increase of polishing time.