Method for improving high-temperature oxidation resistance of Nd-Fe-B permanent magnet

The invention relates to a permanent magnet surface coating protection method, in particular to a neodymium iron boron permanent magnet and a hot dip aliminizing protection method thereof, which belongs to the neodymium iron boron material field. The invention comprises the following process steps that firstly, the surfaces of plating parts are cleaned, to clean oil stain, oxide skin and foreign matters on the surfaces; secondly, the mixture of Al-Si alloy and fluxing agent salt is melted in a vertical resistance furnace, and is heated to 680 to 750 DEG C, to melt the mixture; thirdly, assistant plating is performed in potassium fluorozirconate or potassium fluotitanate solution; fourthly, the plating parts after being plated are dried and pre-heated; fifthly, neodymium iron boron is dipped in a aluminum plating groove mixed with the Al-Si alloy and the fluxing agent salt, to perform hot dip coating, the hot dip coating time is 0.5 to 2 min; sixthly, the plating parts are taken out slowly, to ensure to cool t