An attempt has been made to improve the corrosion behavior of WE43 magnesium alloy by laser surface melting (LSM) using a 10 kW continuous-wave CO₂ laser. The microstructure evolution of WE43 alloy after LSM treatment was analyzed by using scanning electron microscopy, energy-dispersive spectroscopy and metallographic microscope. The corrosion resistance of specimens was assessed by electrochemical and immersion tests. Results showed that the LSM treated WE43 alloy presented a uniform microstructure with refined grains, enriched alloying elements and redistributed intermetallic compounds. The LSM treatment effectively improved corrosion resistance of WE43 alloy, which was mainly associated with enrichment of alloying elements in α-Mg matrix and uniform distributions of the refined Mg₁₄Nd₂Y phase.