Li-rich Li(Li0.125Mn0.375Ni0.5)O2 was prepared by a carbonate co-precipitation method and modified with graphene. The effects of graphene on the surface structure, morphology and low-temperature electrochemical properties of Li(Li0.125Mn0.375Ni0.5)O2 are investigated. The electrochemical performance results show that the charge-discharge capacities and voltages platform are lowered with the reducing temperature, however, cathode materials surface modified by graphene exhibit higher specific discharge capacity and slower voltage fading rate. The electrochemical impedance spectroscopy (EIS) results indicate that the improvement of low temperature electrochemical performance of Li(Li0.125Mn0.375Ni0.5)O2 modified by graphene is originated from the stable interface and higher conductivity.