The invention discloses a synthetic method of cyclosulphate. A peroxysulfate solution is pre-synthesized through sulfuric acid and hydrogen peroxide, then under existence of an organic solvent, a metal inorganic compound and a catalyst, the peroxysulfate solution is dropwise added to generate a catalytic oxidation reaction with cyclosulfite, after the reaction is completed, salt residue is filtered out, still standing for layering is conducted, an organic layer is taken to be distilled, concentrated and purified, and a cyclosulphate high-quality product is obtained. According to the syntheticmethod of the cyclosulphate, the cheap sulfuric acid and hydrogen peroxide are used as the raw materials, the peroxysulfate solution is prepared to conduct catalytic oxidation on the cyclosulfite, onthe one hand, the reaction is mild, control is easy, and the reaction conversion rate is high; on the other hand, the evaporation capacity of water is small, energy consumption is low, generated wastewater is less, and a synthetic process is more environmentally friendly; and the prepared cyclosulphate is few in impurity, high in purity and wide in market prospect.