The invention discloses a long- cycle and high-safety power lithium ion battery positive electrode material and a preparation method thereof. The positive electrode material can be shown as a general formula LiNi<(1-a-b-c)>CoMnM<c>O2.xLiM<1>O<y>, wherein a is greater than 0 and less than 1, b is greater than 0 and less than 1, a+b+c is greater than 0 and less tan 1, x is greater than 0 and less than 0.1, and y is greater than 1 and less than 5; LiNi<(1-a-b-c)>CoMnM<c>O2 is a primary active crystalline particle of the positive electrode material, and is a lithiated composite oxide composed of nickel cobalt manganese and doping element M; and the LiM<1>O<y> is a coating layer coating crystal boundary of the primary active crystalline particle and surface of a polycrystalline secondary particle. The positive electrode material provided by the invention has high stability of crystalline main body, surface and crystal boundary, has good compatibility with electrolyte and is not liable to generate side reaction. The material provided by the invention is used for batteries, has long cycle life, high over-charging resisting capability, good high temperature and high voltage performance and high integral safety, and is particularly suitable for power batteries.