Ti ion and C ion is implanted into AZ31 magnesium alloy surface by metal vapor vacuum arc (MEVVA) implanter operating with a modified cathode. This metal arc ion source has a broad beam and high current capabilities. Implantation energy is fixed at 45K eV and dose is 9×1017 cm-2 and 3×1017 cm-2 respectively. Through ion implantation, Ti ion implantation layer approximately 1000nm thick is directly formed on the surface of AZ31 magnesium alloy, by which its surface property is greatly improved. Microstructure, the component distribution and phase composition are analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The property of hardness of the ion implantation layer was studied by HMV-1T Vickers micro hardness tester. The results show that Ti ion implantation layer of a magnesium alloy surface is mainly composed of TiO2, MgO and a little of TiO. The Ti-C double ions implantation layer is composed of MgO, TiC. The hardness of ion implantation layer is improved.