The invention relates to a method for preparing hydroiodic acid by electrodialysis of a bipolar membrane. The method comprises the following steps: placing a sodium iodide solution in a raw material chamber formed by the bipolar membrane; arranging a cation exchange membrane and an anion exchange membrane on a left side and a right side of the raw material chamber respectively; forming an alkali chamber by the cation exchange membrane and the raw material chamber; forming an acid chamber by the anion exchange membrane and the bipolar membrane of the raw material chamber; forming a bipolar membrane electrodialysis device by the raw material chamber, the acid chamber and the alkali chamber; then, adding distilled water into the acid chamber and adding aqueous solution of sulfuric acid into the alkali chamber in an electric field; when detecting that solubility of NaOH generated by reaction is stable, stopping reaction to respectively obtain aqueous solution of hydroiodic acid and aqueoussolution of sodium hydroxide from the acid chamber and the alkali chamber; and distilling and concentrating the aqueous solution of hydroiodic acid to obtain hydroiodic acid. The hydroiodic acid prepared by the method provided by the invention is a mixed solution having a concentration of hydriodic acid greater than 2.4%; the prepared mixed solution is distilled to obtain hydroiodic acid solutionhaving a higher concentration; and the sodium hydroxide solution having the concentration greater than 2% obtained from the alkali chamber can be recovered as a by-product.