The main technical problem in the preparation of hypereutectic Al-high Si alloy is the refinement of the primary Si particles. In this paper, a new method for the preparation of Al-high Si alloy with refined primary Si particles by filtration treatment is proposed. During this process, the melt of hypereutectic Al-Si alloy underwent the filtration treatment at the temperature of little above the eutectic line in the Al-Si binary phase diagram. After that, the large-sized primary Si particles were retained by the filter screen, while the small-size primary Si particles together with the eutectic melt went through the screen and cooled down, forming into the hypereutectic Al-high Si alloy products. The Si content in the Al-high Si alloy prepared in this study was about 27 wt.%, the average diameter of the primary Si particles reached less than 45 μm, the roundness of the primary silicon particles was 1.43, and the brinell hardness of the alloy was about 70 HB. By this method, it is expected to obtain the Al-high Si alloy with higher degree of sphericity of the primary Si particles and higher Si content.