Abstract: To implement additive manufacturing aluminum/steel dissimilar metals, bypass-current MIG welding technology was conducted with 2 mm thick Q235 galvanized steel and 4043 aluminum filler wire with diameter of 1.2 mm. The T-shaped structure with uniform appearance and excellent performance was obtained. The microstructure, hardness distribution and shear property of the joint were investigated respectively through metalloscope, micro hardness test, universal tensile test machine. The variations of microstructure and mechanical properties of the deposited layer were studied. The results indicated that the bottom of deposited layer on the aluminum side and steel side was composed of thin needles and strip Fe/Al compounds, respectively. The middle of the deposited layer is dendrite structure, and the microstructure at the top of the deposited layer does not show any directional trend growth. The shear tests showed that the maximum shear force of T-shaped structure is 2 108 N. When the shear angle exceeds 13.5 °, the fracture occurs at the roots of the T-shaped structure, and there is no obvious crack in the deposited layer.