Abstract: The present disclosure discloses a modified high-nickel cathode material, where the modified high-nickel cathode material is a SO42--doped modified high-nickel cathode material, and SO42- is distributed in a secondary particle with a content gradient from high inside to low outside. A preparation method of the modified high-nickel cathode material includes: mixing a high-nickel cathode material, a lithium source, and a sulfate, and sintering a resulting mixture to obtain a matrix material; and water-washing and drying the matrix material to obtain the modified high-nickel cathode material. The present disclosure increases a migration rate of lithium ions in the material and greatly improves the initial capacity of the material, which reduces an energy barrier for migration of lithium ions, increases a migration rate of lithium ions among primary particles of the material, and improves the safety performance of the material.