A method for cyclically preparing elemental boron and coproducing potassium cryolite using potassium 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 potassium sulphate aqueous solution to the fluoboric acid to enable a reaction to form a potassium fluoborate precipitate, centrifuging and rinsing the potassium fluoborate precipitate to obtain the intermediate material potassium fluoborate; C) putting dried potassium fluoborate into a reactor, injecting an inert gas to the reactor after vacuumizing, heating the reactor to a temperature of between 700 and 800 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 potassium 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 800 DEG C, adding dried and flowable potassium fluoborate in the reactor and stirring quickly to enable a reaction for 4 to 6 hours to form the elemental boron and potassium cryolite; D) extracting molten liquid potassium cryolite; after the molten liquid potassium cryolite 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 potassium sulphate, potassium sulphate; collecting the hydrogen fluoride gas and dissolving it into water to obtain a hydrofluoric acid aqueous solution; reacting the aluminium potassium sulphate with an aqueous solution of potassium hydroxide after crushing the aluminium potassium sulphate, and obtaining the aqueous solution of potassium sulphate after separating out the solid aluminium hydroxide; and E) recycling the obtained hydrofluoric acid aqueous solution and the aqueous solution of potassium sulphate to the front end to leach the boric acid or boron oxide, so as to achieve the purpose of cyclically preparing the intermediate material potassium 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 potassium sulphate aqueous solution to the fluoboric acid to enable a reaction to form a potassium fluoborate precipitate, centrifuging and rinsing the potassium fluoborate precipitate to obtain the intermediate material potassium fluoborate; C) putting dried potassium fluoborate into a reactor, injecting an inert gas to the reactor after vacuumizing, heating the reactor to a temperature of between 700 and 800 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 potassium 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 800 DEG C, adding dried and flowable potassium fluoborate in the reactor and stirring quickly to enable a reaction for 4 to 6 hours to form the elemental boron and potassium cryolite; D) extracting molten liquid potassium cryolite; after the molten liquid potassium cryolite 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 potassium sulphate, potassium sulphate; collecting the hydrogen fluoride gas and dissolving it into water to obtain a hydrofluoric acid aqueous solution; reacting the aluminium potassium sulphate with an aqueous solution of potassium hydroxide after crushing the aluminium potassium sulphate, and obtaining the aqueous solution of potassium sulphate after separating out the solid aluminium hydroxide; and E) recycling the obtained hydrofluoric acid aqueous solution and the aqueous solution of potassium sulphate to the front end to leach the boric acid or boron oxide, so as to achieve the purpose of cyclically preparing the intermediate material potassium fluoborate.