The invention is applied to the field of lithium batteries, and provides a lithium nickel-cobalt-iron positive electrode material and a preparation method. The method comprises the steps that an indium-iridium-doped nickel-cobalt precursor is prepared and then subjected to mixed sintering with ferroferric oxide micropowder to obtain an indium-iridium-doped nickel-cobalt-iron positive electrode material, then the indium-iridium-doped nickel-cobalt-iron positive electrode material is mixed with a coating agent for secondary sintering, and finally the coating agent-coated lithium nickel-cobalt-iron positive electrode material is obtained. According to the positive electrode material, the crystal structure is stable, the coating layer is not prone to separate, and In<3+> and Ir<3+> are at constant valence in the charging and discharging process, are electrochemically inactive, do not generate valence state changes during charging and discharging or generate size changes, can achieve a skeleton effect and are beneficial to prolonging of the cycle life of the material and improvement of the security performance of the material.