In order to study the corrosion resistance of dissimilar material weld, butt weld joint of 316L and 304 austenitic stainless steel was prepared by laser welding. The microstructure and phases of the weld joint were investigated by optical microscope and X-ray diffraction. The electrochemical corrosion behavior of the dissimilar metal weld joint and two base materials was studied by potentio dynamic polarization test in 3.5% NaCl solution at room temperature. Results show that pitting mainly at grain boundary and the weld exhibits better corrosion resistance in 3.5% NaCl solution compared with base metals. At the same time, the weld has more refined grains, the amount of austenite is increased and the preferential growth of austenite is obvious in weld, which is the main reason for enhancing electrochemical corrosion resistance.