A method for cyclically preparing elemental boron and coproducing sodium cryolite using sodium fluoborate as an intermediate material, including the following steps: A) adding hydrofluoric acid to boric acid or boron oxide to enable a reaction at a temperature of between 100 and 200 DEG C to form fluoboric acid; B) adding a sodium carbonate aqueous solution to the fluoboric acid to enable a reaction to form a sodium fluoborate solution, concentrating, crystallizing and rinsing the sodium fluoborate solution to obtain the intermediate material sodium fluoborate; C) putting dried sodium fluoborate into a reactor, injecting an inert gas to the reactor after vacuumizing, heating the reactor to a temperature of between 700 and 1000 DEG C, adding aluminium in the reactor and stirring quickly to enable a reaction for 4 to 6 hours to form the elemental boron and sodium cryolite, or, putting the aluminium into the reactor, injecting an inert gas to the reactor after vacuumizing, heating the reactor to the temperature of between 700 and 1000 DEG C, adding dried and flowable sodium fluoborate in the reactor and stirring quickly to enable a reaction for 4 to 6 hours to form the elemental boron and sodium cryolite; D) extracting the molten liquid sodium cryolite, after it is cooled, crushing and sending it to a rotary reaction kettle quantificationally together with concentrated sulphuric acid to enable a reaction at a temperature of between 400 and 500 DEG C to form hydrogen fluoride gas and aluminium sodium sulphate; collecting the hydrogen fluoride gas and dissolving it into water to obtain a hydrofluoric acid aqueous solution; reacting the aluminium sodium sulphate with an aqueous solution of sodium hydroxide after crushing the aluminium sodium sulphate, and obtaining an aqueous solution of sodium sulphate after separating out the solid aluminium hydroxide; and E) recycling the obtained hydrofluoric acid aqueous solution to the front end to leach the boric acid or boron oxide, so as to achieve the purpose of cyclically preparing the intermediate material sodium fluoborate. A) adding hydrofluoric acid to boric acid or boron oxide to enable a reaction at a temperature of between 100 and 200 DEG C to form fluoboric acid; B) adding a sodium carbonate aqueous solution to the fluoboric acid to enable a reaction to form a sodium fluoborate solution, concentrating, crystallizing and rinsing the sodium fluoborate solution to obtain the intermediate material sodium fluoborate; C) putting dried sodium fluoborate into a reactor, injecting an inert gas to the reactor after vacuumizing, heating the reactor to a temperature of between 700 and 1000 DEG C, adding aluminium in the reactor and stirring quickly to enable a reaction for 4 to 6 hours to form the elemental boron and sodium cryolite, or, putting the aluminium into the reactor, injecting an inert gas to the reactor after vacuumizing, heating the reactor to the temperature of between 700 and 1000 DEG C, adding dried and flowable sodium fluoborate in the reactor and stirring quickly to enable a reaction for 4 to 6 hours to form the elemental boron and sodium cryolite; D) extracting the molten liquid sodium cryolite, after it is cooled, crushing and sending it to a rotary reaction kettle quantificationally together with concentrated sulphuric acid to enable a reaction at a temperature of between 400 and 500 DEG C to form hydrogen fluoride gas and aluminium sodium sulphate; collecting the hydrogen fluoride gas and dissolving it into water to obtain a hydrofluoric acid aqueous solution; reacting the aluminium sodium sulphate with an aqueous solution of sodium hydroxide after crushing the aluminium sodium sulphate, and obtaining an aqueous solution of sodium sulphate after separating out the solid aluminium hydroxide; and E) recycling the obtained hydrofluoric acid aqueous solution to the front end to leach the boric acid or boron oxide, so as to achieve the purpose of cyclically preparing the intermediate material sodium fluoborate.