A pulsed Nd:YAG laser is used in multi-layer cladding on ZM6 Mg base alloys. The microstructure is studied with an optical microscope and a scanning electron microscope (SEM). The composition within the layer was determined by electron probe microanalysis (EPMA). X-ray diffraction (XRD) was also used to investigate the phase of constitutes of the cladding zone. The results show that microstructure in solidified cladding layer changes much when treated by high energy laser beam. The microstructure of the ZM6 alloy consists of α-Mg and Mg9Nd, while the L-ZM6 of α-Mg, Mg9Nd and α-Zr. The depth of the cladding is over 1 mm. Many fine particles were found to be distributed homogeneously throughout the matrix and the columnar grain grows along substrate.