Abstract: Taking TiO₂ powders as inoculant,the effect of the TiO₂ powders on the refinement and modification of α-Al and eutectic Si phase in A356 was studied. The results show that when the optimum addition of TiO₂ is 0.5wt%,the size of α-Al grain can be reduced to 20 μm,and the morphology of eutectic silicon are modified from needle form to short stick even spherical form.Accordingly,the value of Brinell hardness is increased by 25%to 67.9 HBW.The analysis thinks that the α-Al phase and eutectic Si phase are refined and modified by the aluminum alloy melt and TiO₂ in situ generated γ-Al₂O₃,and the performance of the material is improved by the synergistic particle strengthening of γ-Al₂O₃.