<p>This paper proposed a novel electromagnetic stirring (EMS)-assisted lost foam compound casting (LFCC) process to prepare A356/AZ91D bimetallic materials, and the effects of electromagnetic field intensity on the microstructure and mechanical properties of the Al/Mg interface were investigated. The results indicated that the Al/Mg bimetallic interface can be divided into two regions: the intermetallic compounds (IMCs) area and the eutectic (E) area. The phase composition in the IMCs area consisted of Al₃Mg₂, Al₁₂Mg₁₇, and Mg₂Si, while the E area was composed of Al₁₂Mg₁₇ and <i>δ</i>-Mg phases. In the sample without EMS, the Mg₂Si grains at the interface were coarse and unevenly distributed. The forced convection induced by EMS dispersed the aggregated Mg₂Si particles uniformly, which significantly refined the Mg₂Si grains. EMS increased the elemental diffusion flux in the Al/Mg interface, which increased the thickness of the IMCs area and expanded the distribution of the reinforcing phase (Mg₂Si). But when the magnetic field intensity reached 68.3 mT, the stronger Archimedean electromagnetic force caused the Mg₂Si particles to collide and form clusters, which was detrimental to the interface properties. In addition, EMS effectively broke the Al₁₂Mg₁₇ dendrites in the E area. EMS resulted in a more uniform distribution of microhardness in the IMCs area. When the magnetic field intensity was 53.8 mT, the shear strength of the Al/Mg bimetallic sample treated with EMS reached 55.7&#xa0;MPa, which was a 70.9 pct improvement over the untreated sample. This enhancement was attributed to the grain refinement and the uniform distribution of Mg₂Si phase, which reduced stress concentration in the interface. In addition, the EMS significantly refined the AZ91D matrix microstructure, demonstrating that the magnetic field has a unique advantage in enhancing bimetallic properties: it can simultaneously optimize both the interface and the matrix microstructure.</p>