The invention discloses a ternary positive electrode material, a preparation method thereof and a lithium battery, and relates to the field of lithium batteries. The ternary positive electrode material is a high-nickel ternary positive electrode of which the bulk phase is doped with an M element and the surface layer is doped with an N element. The chemical formula of the ternary positive electrode material is LiNixCoyMn<1-x-y>MaNbO<2+(a+b)/2>, wherein x is greater than 0.8 and less than 1, y is greater than 0 and less than 0.2, a is greater than 0.002 and less than 0.8, and b is greater than0.0001 and less than 0.03. The preparation method of the ternary positive electrode material is controllable in operation, the prepared ternary positive electrode material improves the stability of the internal structure through bulk phase doping of non-variable-valence M ions, the transmission efficiency of Li in the structure of the ternary positive electrode material is improved, the corrosionof an electrolyte to the positive electrode material is effectively relieved by doping inert ions N on the surface layer, and the cycle performance and the rate capability are effectively improved through the reasonable doping and mutual cooperation.