<p>Oscillating laser welding is employed in joining of 6061 Al alloy to 304 stainless steel (304 SS) in a butt configuration. Effects of the welding parameters on macro/micro-structures and mechanical properties of the joint are investigated. A maximum strength of 117 MPa is achieved at the optimal process parameters combination, specifically, an oscillation frequency of 60 Hz, offset towards 304 SS side, a defocusing distance of −&#xa0;2 mm and welding speed of 1.0 m/min. The results shows welding speed considerably affects the interfacial morphology and joint property. At a lower welding speed of 0.8 m/min, excessive heat input per unit length induces extensive melting on Al side, forming a large molten pool and a curved multi-layered interface. Under the stirring action of laser oscillation, Al and Fe atoms undergoes inhomogeneous mixing, leading to the formation of numerous intermetallic compounds (IMCs) and low tensile strength. Conversely, when the welding speed increases to 1.2 m/min, the insufficient heat input prevents the significant melting of Al, while the laser oscillation fails to promote adequate mixing of Al and Fe. Consequently, the Al/Fe interface is relatively smooth with a small amount of IMCs, causing a lower joint strength. The types of IMCs are kept unchanged with different welding speeds, mainly consisting of FeAl₃, Fe₂Al₅, FeAl, and FeAl₂. All the joints fracture at the weld same and exhibit predominantly brittle fracture characteristics.</p>