The invention discloses a lithium ion battery positive electrode material and a preparation method and application. The preparation method of the lithium ion battery positive electrode material comprises the following steps of (1) dissolving a soluble nickel salt, a soluble cobalt salt and a soluble manganese salt in deionized water to obtain a mixed metal ion salt solution with certain concentration, wherein the valence states of nickel, cobalt and manganese in the nickel salt, the cobalt salt and the manganese salt are all right bivalent; (2) adding the mixed metal ion salt solution into a kettle reactor, simultaneously adding a sodium carbonate solution, adding ammonia water again to adjust a pH value to 8-11, controlling a temperature to 55-60 DEG C, performing protection with an inert gas, and performing continuous stirring; (3) filtering a carbonate precursor solution, washing the product with the deionized water, and placing the product a drying oven for drying; and (4) grinding precursor powder, performing pre-sintering, adding anhydrous potassium carbonate, performing mechanical ball-grinding, and performing high-temperature solid-phase sintering to obtain the positive electrode material with a chemical formula K<x>(Ni<y>Co<z>Mn<1-y-z>)O<2>. The preparation method has the advantages of simple operation, short period and low cost.