Galvanized steel and AISI 304 stainless steel are lap-welded by a pulsed-NdYAG laser. The weld joint is of good surface quality based on the shear strength which reaches its work requirement. The effects of the laser welding process parameters such as laser current, welding speed and defocused distance on the shape of the weld seam are investigated. The optimum welding parameters are I=350 A, V=100 mm/min, ΔF=-1 mm,f=4 Hz, W=10 ms, and there is no weld trace on the back of AISI 304 stainless steel at the same time. The microstructure of the welded seam is martensite and residual austenite, and close to the side of galvanized sheet, there is a small amount of pearlite. Because of the existence of martensitic hardened layer, the microhardenss in the weld seam and heat affected zone is higher than that of the base metal.