Through controlling the related processing parameters of continuous wave CO2 laser, LY12CZ surface was remelted by laser and after remelting the fatigue test, fatigue fracture, microstructure and micro-hardness were analyzed. The result showed that there was no obvious difference between the fatigue life of specimen with and without laser remelting. The fatigue fracture indicated that the fatigue crack resource was at the surface of remelting region, and the crack extended along the grain boundary of the columnar crystal and broke suddenly in the substrate. After remelting, the grains at the surface were obviously fined, and the micro-hardness of the surface was improved by 40% in contrast to substrate.