The invention discloses a method for enhancing the electricity producing performance of a CO2 mineralization battery by using mirabilite and a battery thereof. A cation exchange membrane separates a battery container into an anode region and a cathode region; the anode region is a solution containing mirabilite and calcium hydroxide; the cathode region is a sodium bicarbonate solution; after an electric path is formed, CO2 is introduced into a cathode region; H<+> and HCO<3-> are obtained through ionization; the H<+> is reduced into H2 at a cathode, is circulated back to an anode to be oxidized into H<+>, and is then neutralized with OH<-> ionized from calcium hydroxide; the HCO<3> and Na<+> transmitted from the anode region produce sodium bicarbonate; Ca<2+> and sulfate radicals of the mirabilite generate calcium sulfate precipitates; the sodium bicarbonate in the cathode region is subjected to removal filtering to obtain sodium bicarbonate solids; or further drying is performed to obtain sodium carbonate solid; the calcium sulfate generated in the anode region can be used as cement production raw materials after being treated. The mirabilite with rich resources are used as reaction media to replace sodium chloride, so that the electricity producing performance and the open circuit voltage of the CO2 mineralization battery are also improved; the battery structure is greatly simplified.