The work aims to improve the wear resistance and corrosion resistance of Ni-P-SiC composite coating on the surface of magnesium alloys. Ni-P electroless plating solution with SiC particles was used to prepare Ni-P-SiC composite coating on the surface of AZ91D Mg alloy, and the composite coating was heat treated at different temperature. Then the microstructure, micro-hardness, wear resistance and corrosion resistance of the composite coating were analyzed and evaluated by virtue of XRD, micro-hardness test, electrochemical corrosion test and friction-wear test. After thermally treated at 320 ℃, the microstructure of Ni-P-SiC composite coating transformed from amorphous into crystal microstructure accompanied with precipitation of Ni3P phase. Micro-hardness of the Ni-P-SiC composite coating subject to heat treatment at the temperature was up to 1120HV, 1.81 times higher than that of the coating not subject to heat treatment (620HV); Ecorr of the Ni-P-SiC composite coating was –0.697 V, higher than that of the coating not subject to heat treatment (–0.727 V); value of Jcorr was the lowest (0.984 μA/cm–2), and wear volume of Ni-P-SiC composite coating was the lowest as well (0.324×10–3/mm3). When the heat treatment temperature was 340 ℃, the wear volume of Ni-P-SiC composite coating was up to 1.43×10–3/mm3. After being heat treated at 320 ℃ for 1h, micro-hardness, corrosion resistance and wear resistance of the Ni-P-SiC composite coating prepared on the surface of AZ91D Mg alloy are all increased.