Abstract: A high-nickel ternary core-shell precursor for a lithium battery, a positive electrode material and a preparation method therefor. The chemical structural formula of the precursor is zNi(C4H7N2O2)2—Nix-zM1yM21-x-y(OH)2, wherein M1 and M2 are two of cobalt, aluminum, and manganese. The preparation method comprises: pumping a prepared metal salt solution, a dimethylglyoxime-ammonia water composite solution, and an ammonia water solution into a reaction kettle, maintaining the pH of a reaction system, and controlling the reaction time to obtain a sphere-like precursor inner core with a structural formula of Ni(C4H7N2O2)2; pumping the metal salt solution and the ammonia water solution, stopping pumping the dimethylglyoxime-ammonia water composite solution, pumping a sodium hydroxide solution to obtain a sphere-like core-shell precursor, washing, drying, sieving and deironing the precursor, mixing with a lithium source, and calcining to prepare the positive electrode material.