A compound casting process combined with hot-dip galvanizing was used to produce an aluminum/steel bimetal, obtaining a superior metallurgical interface that mainly consisted of τ6-Al4.5FeSi, Al-Zn eutectic and Si phases. Under as-cast condition, the aluminum/steel bimetal had a relatively low bonding strength, resulting from the poor morphology and size of the τ6-Al4.5FeSi phase and the Si particles. An appropriate heat treatment procedure greatly improved the interfacial microstructure and bonding strength of the aluminum/steel bimetal, and the phase compositions in the interface were nearly similar to that of the as-cast condition. The excessive heat treatment promoted the excessive growth and cracks of the interface layer, sharply weakening the bonding strength of the aluminum/steel bimetal. With a solution temperature of 500 °C for 2 h, the shear strength of the aluminum/steel bimetal significantly increased by 39% in comparison with that of the as-cast sample, which was mainly attributed to the improvements of the morphology and size of the τ6-Al4.5FeSi phase and the Si particles. No excessive growth of the interface layer and the absent of the crack defect were also responsible for the improvement of the shear strength of the aluminum/steel bimetal.