Abstract: The magnesium/aluminum composite material was prepared by solid-liquid composite casting technology, and the effect of adding 1.5wt% Sr element in pure magnesium on the interface of the composite material was studied by SEM, XRD and other detection techniques.The results show that the pure magnesium/pure aluminum composite interface undergoes eutectic reaction of magnesium and aluminum to form a eutectic structure (α-Mg+Al₁₂Mg₁₇), that is, there are a large number of brittle phases Al₁₂Mg₁₇ and Mg₂Al₃ phases at the interface and along the interface (the direction of temperature gradient decrease) and it grows perpendicular to the Al side to the Mg side, and the brittle phase at the magnesium matrix presents a fishbone shape with a certain directional aggregation.After the addition of Sr element, the number of brittle phases at the composite interface is not only reduced, but also its morphology is changed.The dense Al₁₂Mg₁₇ and Mg₂Al₃ aggregates in the form of fishbone no longer appearing, and the brittle phases growing vertically at the composite interface are reduced or even disappear.