The invention discloses a neodymium iron boron waste double-flash supergravity slag metal melting comprehensive recovery method. According to the method, neodymium iron boron waste and oxygen-rich airare sprayed into a reaction tower through a spray nozzle, the materials float down to the lower end from the upper end of the reaction tower in a highly dispersed floating state, and rare earth and iron in the materials are fast and fully oxidized; oxidation products and reducing gas are sprayed into another reaction tower through a spray nozzle, most of ferric oxide is reduced into metal iron, and the small amount of iron not reduced is reduced into metal iron when passing through a molten coke layer; and molten iron and rare earth slag high-temperature mixed melt enters a supergravity slagmetal melting device, under the effect of supergravity, molten iron permeates porous ceramic filter film, rare earth slag is retained in a drum, accordingly, efficient enriching and separation of therare earth and iron in the neodymium iron boron waste is achieved, the defects that a traditional neodymium iron boron waste treatment method is long in process, high in energy consumption, large in acid dissolution iron slag amount, low in rare earth recovery rate, difficult in iron resource recovery are overcome, and the economic and environment friendliness benefits are good.