The invention provides a high-voltage lithium cobaltate positive electrode material, a preparation method thereof and a lithium-ion secondary battery. The high-voltage lithium cobaltate positive electrode material is a multi-stage core-shell structure and comprises a lithium cobaltate core layer of an alpha-NaFeO2 structure, a composite doped layer and a functional shell layer from the inside to the outside, the general formula of the high-voltage lithium cobaltate positive electrode material is LiCoO2.D-LiCo1-xMxO2.S-Li-La-X-O, x is larger than or equal to 0.01 and smaller than or equal to 0.06, M is one or more elements in the group consisting of Al, Ti, Zr, La, Nb and rare earth elements, and X is one or more elements in the group consisting of Zr, Nb, Sc and Ga. According to the invention, through the high-temperature sintering of the lithium cobaltate core layer coated with the functional shell layer, the material of the functional shell layer is doped into a lithium cobaltate surface layer, therefore, the structure of lithium cobaltate is stabilized, the phase change of the lithium cobaltate in a high-voltage discharge process is inhibited, and the cycle performance and rateperformance are improved.