Abstract: The CO2 laser welding was used to weld ZK60 magnesium alloy sheets, and the microstructure of different zones in the welded joint, phase compositions of the weld seam and the properties of weld joint were studied. The results show that the obvious partial melted zone appeared in the weld seam of ZK60 magnesium alloy, the weld seam was narrow and its forming was good. The microstructure of weld seam zone was composed of fine equiaxed grains, and the MgZn, MgZn2 precipitated phases were found at grain boundaries and in grains, which were not exist in the base metal. The tensile strength of the welded joint could achieve 81.1% of the base metal, and the hardness of the weld seam was 66 HV, and which was slightly lower than that of the base metal.