In this paper, the research on control of intermetallic compound during aluminum/steel friction stir lap welding is reviewed. Several means that improve the properties and quality of the joints are presented by controlling the IMCs layer. The thickness of IMCs layer is controlled by the processing parameters, tool structure and aided processing, and the types of the IMCs are controlled by the processing parameters and the addition of the interlayer design. Advantages and disadvantages of the above methods are discussed. A new research direction with a large-lift angle structure of the tool is also proposed for the development of the aluminum/steel welding technology in this paper.