Abstract: Lap joint friction stir welding of dissimilar materials between DP600 dual-phase zinc-coated steel and industrial pure aluminum 1060(the aluminum plate was on the top and the steel was under it) was researched in this paper. It can be found from microstructure morphology of the joint that the steel inserts the aluminum just like two nails in both the advancing side and return side. On the micro scale, the steel and aluminum fully mixed together like rivers. In the weld, nugget zone and heat affected zone, a layer of a certain width of the transition layer was formed by the two materials staggered together. Mechanical performance tests show that the hardness of transition layer is high, joint shear strength is about 77% of base metal, and the mechanical properties of the weld is good. Intermetallic compound Al₁₃Fe₄ is found on the fractured surface through XRD phase analysis.