The welding processing of Mg-rare earth alloy NZ30K was studied using laser-TIG hybrid welding. For comparison the NZ30K alloy was also welded by the gas tungsten arc (TIG) and laser beam respectively. The microstructure of the welded joints had been analyzed. The hybrid welding method could refine the grains in the fusion and improve the tensile strength of the welded joints obviously. The arc plasma and the laser-induced plasma during welding were recorded by a high speed camera and the area of the plasma was calculated through image processing technology. Among the three welding processes the plasma area of the hybrid welding is the largest, but not a simple addition of the TIG welding and laser welding. The results show that Mg-rare earth alloy NZ30K can be well joined using the laser-TIG hybrid welding method.