Abstract: The modification of eutectic Si in modified hypoeutectic Al-Si alloy is of great significance to improve the mechanical properties of the alloy. Sr element is an effective chemical modifier. The experimental results of eutectic Si of hypoeutectic Al-Si alloy modified by Sr were summarized and analyzed, and the following conclusions are got: Sr element can effectively modify eutectic Si of hypoeutectic Al-Si alloy, and it changes eutectic Si morphology from plate to fibrous and granular.However, the modification effect is related to many factors, such as adding temperature of Sr during melting, holding time, cooling rate of alloy solidification, etc. When Sr and other elements participate in eutectic Si modification of hypoeutectic Al-Si alloy, the coupling relationship between two elements might not be invariable, such as Sr and B. At present, there is no unified understanding on the modification mechanism of eutectic Si modified by Sr element, but Al₂Si₂Sr plays a very important role in the modification of eutectic Si.