Abstract: The present invention provides a method of manufacturing ultra-pure sulfuric acid. Industrial sulfur trioxide is used as the raw material, gasifying it in a round gasifier, getting it gasified for the second time after condensation, sulfur trioxide gas has been purified. Absorbing the sulfur trioxide gas with the dilute sulfuric acid circularly, collect the target product of ultra-pure sulfuric acid. The main content of the ultra-pure sulfuric acid obtained by the method of the present invention can reach more than 96 wt %, the content of the impurities of metal ions is in conformity with the SEMI C12 standard.