Abstract: The Li-rich layered Li1.166(Mn0.6Ni0.2Co0.2)0.834O2 cathode materials have been successfully synthesized through hydrothermal method. The structure and morphology of the material were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the electrochemical performance were tested by battery test systerm, the results indicate that the sample Li1.166(Mn0.6Ni0.2Co0.2)0.834O2 shows the great feature on the surface of a polyhedron and excellent electrochemical performance. The first charge and discharge capacities of the sample is 363.8 and 222.2 mAh g?1, respectively, with an initial coulombic efficiency of 61.1 % at a constant density of 25 mA g?1 . A reversible discharge specific capacity of approximately 235.5 mAh g?1 is still obtained after 100 cycles. The discharge capacities of 225.6, 198.3, 162.5, 133.2 and 98.3 mAh g?1 can be obtained at 0.1C, 0.2C, 0.5C, 1C and 2C, respectively. The rich lithium Li1.166(Mn0.6Ni0.2Co0.2)0.834O2 cathode material in the development of high energy density of power battery has good application and broad market space.