Mg-doped composite, Li2.97Mg0.03VO4, with an orthorhombic structure was prepared by a sol-gel method. The effects of the Mg doping on the structure and electrochemical performance of Li3VO4 were investigated. The X-ray diffraction pattern shows that the Mg doping does not change the crystal structure of Li3VO4. The EDS mappings indicated the fairly uniform distribution of Mg throughout the grains of Li2.97Mg0.03VO4. Electronic conductivity of Mg-doped Li3VO4 increased by two orders of magnitude compared to that of pure Li3VO4. CV and EIS measurement confirms that the Li2.97Mg0.03VO4 sample exhibits a smaller polarization and transfer resistance and a higher lithium diffusion coefficient compared with the pure Li3VO4. Due to the better electrochemical kinetics properties, Mg-doped Li3VO4 showed a significant improved performance compared to the pure Li3VO4, especially for the high rate capability. At the higher discharge/charge rate (2C), the discharge and charge capacities of 415.5 and 406.1 mAh/g have been obtained for the Li2.97Mg0.03VO4 which is more than three times higher the discharge/charge capacities of Li3VO4. The discharge and charge capacities of pure Li3VO4 are only 126.4 and 125.8 mAh/g respectively. The excellent electrochemical performance of Li2.97Mg0.03VO4 enables it as a promising anode material for rechargeable lithium-ion batteries.