The disclosure discloses a method for preparing a permanent magnet material. In this method, an ionic liquid electroplating process is used to electroplate a heavy rare earth metal onto a surface of a sintered magnet to form a magnet with a coating, wherein the sintered magnet has a thickness of 10 mm or less in at least one direction; in the ionic liquid electroplating process, an electroplating solution comprises an ionic liquid, a heavy rare earth salt, a group VIII metal salt, an alkali metal salt and an additive, an anode is a heavy rare earth metal or a heavy rare earth alloy, a cathode is the sintered magnet, an electroplating temperature is 20-50° C., an electroplating time is 15-80 min. The preparation method of the disclosure can improve an intrinsic coercive force of the magnet with low cost and high production efficiency. A utilization rate of heavy rare earth is high.