Pure Al and Al-30％ Al2O3 composite coatings are prepared on the surface of AZ31B magnesium alloy by low-pressure cold spraying. The morphology and structure of the coatings are analyzed by scanning electron microscope(SEM),energy dispersive spectroscopy(EDS),and X-ray diffraction(XRD),and the effects of the addition of Al2O3 on the microstructure of the Al-based coatings are discussed. The mechanical properties and corrosion resistance of the coatings are fully evaluated by the micro-hardness tester, electronic tensile machine, and electrochemical workstation. The results show that the coating structure is more uniform and denser,and the porosity is significantly reduced after the addition of Al2O3. The interfaces between the coatings and the magnesium alloy substrate are distinct,and the coatings and the substrate are mechanically combined. Compared with the pure Al coating,the microhardness of the Al-Al2O3 composite coating is increased to 61.1 HV0.2,and the bonding strength reaches above 53.1 MPa. The self-corrosion potential of the two coatings is higher than that of the magnesium alloy, and the self-corrosion current density is significantly lower than that of the magnesium alloy substrate. The Al-based coatings prepared by low-pressure cold spraying have high hardness,good bonding strength,and good corrosion resistance,which can be used for the repair and protection of magnesium alloy structural parts.