The invention discloses a preparation method of a high corrosion resistant sintered NdFeB magnet. The method is characterized by comprising the following steps of (1) metal-based alloy coating treatment: preparing a metal-based alloy coating on the surface of the sintered NdFeB magnet by adopting an arc spraying process; (2) closed primer coating treatment: coating the surface of the metal-based alloy coating with a silicone coating to form a closed primer coating; (3) topcoat coating treatment: coating the surface of the closed primer coating with a topcoat paint to form a topcoat coating prepared by nanometer particles and modified acrylic epoxy resin by mass, wherein the mass percentage of the nanoparticles is 5.25%, and the balance is the modified acrylic acid epoxy resin. The preparation method has high bonding strength and high corrosion resistance.