This paper aims to study the corrosion and wear of Al-Mg2Si composite coating by spraying it on AZ31B magnesium alloy surface. The corrosion resistance and wear resistance of coatings with different composition proportions were characterized by scanning electron microscopy, electrochemical testing, friction wear testing machine and ultra-depth three-dimensional Microscope. It showed that the corrosion resistance of Al-Mg2Si composite coating sealed was much higher than that of AZ31B magnesium alloy, and the less the content of Al, the more obvious the potential shift was. The positive displacement of Al (20%)-Mg2Si coating was the most, which was shifted 0.5288 V, and the corrosion current density was minimum 3.298×10?6 A/cm2. Furthermore, the less the amount of Al addition, the smaller the wear rate and friction coefficient of the coating, and the wear rate that was 2.48×10?4 mm3/(N?mm) and friction coefficient which was 0.25 were lower when the content of Al was 20%. The less Al content of Al-Mg2Si composite coating is, the better the corrosion and wear resistance are.