Abstract: 6061 aluminum alloy/ DX51D steel dissimilar metals were welded by resistance spot welding, the effects of spot welding current, spot welding time and spot welding pressure on the cross-section morphology, interfacial intermetallic compound (IMC) morphology and tensile shear force of dissimilar metal welded joint were studied.The results show that with the spot welding current increasing from 5kA to 11kA or the spot welding time increasing from 50 ms to 350 ms, the nugget diameter increases, the indentation depth increases, the tensile shear force first increases and then decreases, and the morphology of the IMC at the interface gradually evolves from flat, tongue like, serrated to coarse needle like intermetallic compound at the aluminum side.With the spot welding pressure increasing from 1.5 kN to 3.0 kN, the nugget diameter decreases gradually, the indentation depth increases gradually, and the tensile shear force first increases and then decreases, and the change of the IMC thickness is small.The suitable spot welding parameters for 6061 aluminum alloy/ DX51D steel dissimilar metals are spot welding current of 9 kA, spot welding time of 250 ms and spot welding pressure of 2.5 kN.