The invention relates to a preparation method of a multi-component nanograin growth inhibitor with the chemical formula shown as follows: (M1x, M21-x) (Cy, N1-y). The preparation method comprises the following process steps of: (1) proportioning; (2) preparing a solution or turbid liquid in deionized water or distilled water by using all raw materials, and then, heating, dying or carrying out spray drying on the solution or turbid liquid to obtain precursor powder, wherein the raw materials are measured in the step (1); and (3) sintering the precursor powder in a reaction furnace, introducing nitrogen gas as reaction and proactive gas to the reaction furnace when the temperature is raised to 400-600 DEG C, preserving the heat of 600-650 DEG C for 10-30min, controlling the pressure of the nitrogen gas at 0.01-0.1MPa, then, continuing to heat to 950-1400 DEG C, preserving the heat for 1-2h, carrying out carbon thermal reduction nitridation reaction, after the heat preservation is ended, cooling a reactant to the room temperature along with the furnace, and taking the reactant out of the furnace to obtain the multi-component nanograin growth inhibitor, wherein the precursor powder is prepared in the step (2).