Abstract: Using AlSi5 flux-cored wire and AlSi12 flux-cored wire as filler metal, CMT welding-brazing was used to connect 5086 aluminum alloy and Q235 steel. The macroscopic morphology, microstructure and mechanical properties of the brazed joint under different welding wire compositions and different parameters were studied. The results show that the formed intermetallic compound layer when the AlSi5 flux-cored wire is used as the filler metal is thicker than that formed by the AlSi12 flux-cored wire, which indicates that the Si element can inhibit the formation of the intermetallic compound layer.The fracture analysis through EDS and XRD reveals that Fe₂Al₅and AlMg₄Zn₁₁are formed when the AlSi5 flux-cored wire is used as the filler metal, and Fe₄Al₁₃, Al₆CuMg₄, Al_0.403Zn_0.597 are mainly formed when the AlSi12 flux-cored wire is used as the filler metal. Under the optimal parameters, the average tensile strength of welded joint when AlSi5 flux-cored welding wire is used as filler metal can reach 130.6 MPa, while the average tensile strength of welded joint when AlSi12 is used as filler metal can only reach 106.6 MPa.