The work aims to enhance corrosion and wear resistance of magnesium alloys. Ni-P-SiC composite coating was prepared by depositing AZ91D magnesium alloy in Ni-P electroless plating solution with 3 g/L SiC particle for different deposition time. Thickness, surface roughness, microhardness, wear and corrosion resistance of Ni-P-SiC composite coating were analyzed and evaluated with SEM, roughmeter, electrochemical corrosion and wear tests. The thickness and surface roughness of Ni-P-SiC composite coating increased as deposition time increased. When the deposition time was 150 min, the thickness and roughness were 53 μm and 2.5 μm, respectively; when the deposition time was 120 min, the maximum microhardness was 641HV, corrosion and wear resistance were the best, Ecorr, Jcorr and wear volume were ?0.73 V, 0.78 μA/cm2 and 1.04×10?3 mm3, respectively. Compared with the AZ91D magnesium alloy, the sample produced after deposition exhibited better corrosion resistance after deposition, indicating that the Ni-P-SiC composite coating has improved corrosion resistance of the Mg alloy effectively. The properties of Ni-P-SiC composite coating are significantly influenced by deposition time. And the composite coating obtained at the deposition time of 120 min has better corrosion and wear resistance.