Laser remelting (LSM) was applied on cast high-Mn aluminum bronze (MAB). Then the effect of LSM on the microstructure, corrosion and cavitation erosion behavior in 3.5%NaCl solution for the cast MAB was studied via microstructure observation, electrochemical test and ultrasonic vibration cavitation test. The results showed that in comparison with the as cast bronze, the LSM bronze presents a microstructure of much finer and much homogeneously distributed crystallites, as well as a hardness of 45% higher. During electrochemical test, the LSM bronze shows more or less the same anodic and cathodic processes as that of the as cast one, however the cast bronze had a lower corrosion potential, indicating higher corrosion tendency. After cavitation erosion test in 3.5%NaCl solution for 5 h the weight loss rate of the LSM bronze was only 3/5 of that of the as cast one. Accordingly, the surface damage of the LSM bronze was much lighter with a similar damage degree everywhere, whilst the surface roughness of the LSM bronze was obviously smaller than that of the as cast one. In 3.5%NaCl solution, the synergy between corrosion and cavitation erosion deteriorated the surface damage. For both the as cast and the LSM bronze, the mechanical impact was the dominated factor for the cavitation erosion damage. For the cast bronze, the mass loss caused by the pure cavitation erosion accounted for 71.1% of the total mass loss and 50.8% for the LSM bronze.