In order to improve the corrosion and wear resistance of AZ31B magnesium alloy, Ni alloy cladding layer which had no crack and hole on AZ31B magnesium substrate was created by a 5kW continuous wave CO2 laser. The microstructure was analysed by means of OM(Optical Microscope) and XRD(X-ray Diffraction), the electrochemical corrosion and the abrasion performance were also tested by electrochemical corrosion equipment and the abrasion testing machine. The results show that: the Ni alloy cladding layer can combine with the substrate metallargically, the microstructure of cladding layer is dendritic crystal, and becomes fine significantly from the interface to surface, and the phase of the cladding layer are MgNi2、Mg2Ni、Mg2Ni3Si、Mg2Si and FeNi. Micro-hardness of the cladding layer is 470~601HV which is improved 840%~1102% to the substrate(40~50HV). Average friction coefficient of the cladding layer is 0.321 lower than AZ31B substrate, and the wear mass loss is 91.43% less than the substrate, the wear resistance of the cladded layer has been improved observably. The corrosion voltage of cladding layer moves 136~417mV to plus direction compared to AZ31B magnesium substrate, and the corrosion current of the cladding is 2~3 stages lower.