Abstract: Objective Resistance spot welding of Q355 steel/6061 aluminum alloy was studied by presetting Ni/Zn interlayer. Methods Under different welding time, welding current and electrode pressure, resistance spot welding process of 6061 aluminum alloy and Q355 steel was compared and analyzed, and the optimal resistance spot welding parameters were obtained. Then, by adding Ni/Zn foil between aluminum alloy plate and steel plate, effect of Ni/Zn interlayer on microstructure and properties of aluminum/steel resistance spot welded joints was studied. Microstructure, element proportion, change of second phase and tensile-shear force of aluminum/steel resistance spot welded joints with Ni/Zn interlayer were studied by means of optical microscope, scanning electron microscope, energy spectrum analysis and tensile testing machine. Results The results showed that aluminum/steel spot welded joints were composed of nugget on the side of aluminum, nugget on the side of steel and intermetallic compounds at the bonding interface, which had typical characteristics of double nuggets. Adding Ni and Zn foil to the middle between 6061 aluminum alloy and Q355 steel separately hindered the formation of brittle Al-Fe intermetallic compounds. The addition of Ni interlayer led to the formation of a better ductile Al₃Ni at the interface of welded joints, thereby hindering the formation of hard and brittle Al-Fe intermetallic compounds. The addition of Zn interlayer generated a certain amount of Fe₂Al₅Zn_0.4 at the interface of welded joints, which reduced the thickness of Al-Fe intermetallic compounds layer to 2.88 μm, and achieved the maximum tensile-shear force of 4.69 kN. Conclusion After the addition of Ni/Zn interlayer, nugget diameter and tensile-shear force of aluminum/steel resistance spot welded joints increased, and the addition of Ni element would generate Al₃Ni phase with good toughness at the aluminum/steel interface, thus hindering the formation of Al-Fe intermetallic compounds.