Powder metallurgy (PM) method to fabricate 6.5% silicon steel attracts much attention due to the lower energy consumption and cost. In this paper, Fe-6.5%Si alloy was prepared by spark plasma sintering (SPS) from the mixture of Fe and FeSi powders with different size. The sintering process was investigated through the shrinkage behavior, phase change and microstructure. The results show that the shrinkage starts from 500°C, lower than conventional sintering methods. The sintering temperature and FeSi powder size influence the reaction between Fe and FeSi.