Abstract: In this study, magnesium alloy and stainless steel were laser welded using zinc sheets of varying thicknesses as the interlayer. The phase composition of each region was characterized through optical microscopy and scanning electron microscopy, while the hardness distribution across the weld joint was evaluated via microhardness testing. A zinc layer thickness of 0.1 mm yielded optimal weld joint performance. Under welding conditions of 3.8 kW power, 9.0 Hz frequency, 0.8 mm/s speed, and a shielding gas flow rate of 7 L/min, a fine and uniform grain structure was achieved. The maximum hardness values for stainless steel, magnesium, and zinc were 296.4 Hv, 72.3 Hv, and 110.3 Hv, respectively. Compounds such as MgO and Mg(OH)² may form on the alloy surface. This investigation systematically analyzed the microstructure and mechanical properties of the weld joints between magnesium alloy and stainless steel with different zinc layers, proposing an effective method to enhance the welding quality of dissimilar alloys. This research holds significant theoretical and practical value for advancing the welding of magnesium alloy and stainless steel dissimilar materials.