An automatic high velocity arc spraying process was used to deposit a type of FeCrBSiMoNbW amorphous/nanocrystalline coating with substrate of AZ91 magnesium alloy. The microstructure of the coating was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDAX). The coating is about 250μm in thickness with low porosity and oxids. The results show that the microstructure of the coating can be classified into two regions, namely, a full amorphous phase region and homogeneous dispersion of α-Fe (Cr) nanocrystals with 30-80 nm in a residual amorphous region. Mechanical properties, such as nano-hardness, elastic modulus, were analyzed. The experimental results show that the coating has high nano-hardness and elastic modulus. The friction and wear experiments were operated on UMT-2 micro friction tester. The relative wear resistance of the FeCrBSiMoNbW coating is about 2 times higher than that of the conventional 3Cr13 coating under the same conditions. The main wear mechanism of the amorphous/nanocrystalline coating is the typical brittle spalling.