The invention provides a cathode material of a lithium ion battery. The cathode material comprises a high-capacity cathode active material, a lithium supplementing material, a conductive agent and a binder, wherein the mass percentage ratio of the high-capacity cathode active material to the lithium supplementing material to the conductive agent to the binder is (77-97%):(1-15%):(0.1-3%):(1-5%); the chemical formula of the lithium supplementing material is LixMyNz, x is larger than or equal to 1 and smaller than or equal to 8, y is larger than or equal to 1 and smaller than or equal to 6, z islarger than or equal to 1 and smaller than or equal to 6, M is one or more metal elements of Fe, Cu, Mn, Zr, Mg and Al, and N is one or more non-metal elements of O, N, F, B and S. The invention alsoprovides a preparation method of the cathode material of the lithium ion battery and the lithium ion battery. According to the cathode material of the lithium ion battery, the preparation method andthe lithium ion battery provided by the invention, the capacity exertion of the cathode active material can be improved, the active lithium consumed by the first irreversible capacity loss is well compensated, and the energy density of the lithium ion battery is further improved.