A magnetic field is introduced into the laser welding process, and the butt welding experiment of DC51D+AZ galvanized steels and 6061 aluminum alloys and the tensile experiment of welding samples are conducted. The influences of the alternating magnetic field on weld formation, porosity defects, fracture morphologies, intermetallic compounds, and mechanical properties of Fe/Al welding joints are investigated. The results show that the tensile strength of welding joints is improved after the introduction of the magnetic field. The magnetic stirring can improve the welding morphology, reduce the number of pores in welding joints, refine the acicular FeAl3 phase, and inhibit the growth of brittle Fe/Al compounds, which thus improves the mechanical properties of welding joints.