The fluxless fusion welding-brazing result between 6061 aluminum alloy and galvanized steel with filler material is studied by using rectangular laser beam. The dependence of the mechanical properties on solidification behavior is established based on the joint formation and the weld microstructure. The results indicate that a fusion welding-brazing weld of AA6061 and galvanized steel without flux can be achieved using the welding with filler powder. By optimizing the welding parameters, the favorable weld without crack and porosity can be achieved. The weld width and the thickness of intermetallic compounds layer increase with laser energy input increasing. The intermetallic in the weld is composed of Al-Fe and Al-Fe-Si system phases. Specimens are fractured at the weld/steel interface with the brittle characteristic during tensile test. The weakness of the joint is the weld interface. The maximum intensity of 152.5 N/mm is obtained. Al5Fe2Zn0.4 and α-Al are found in the fracture surface on the aluminum side. The intensity of joint is both determined by weld width and the thickness of intermetallic compound layer.