The invention relates to a method for using sulphur gas for reducing waste sulfuric acid to prepare liquid sulfur dioxide and sulfuric acid. Sulphur is gasified into the high-temperature sulphur gas,the raw material waste sulfuric acid is washed, evaporated, concentrated and split into gas, the two streams of gas is reacted in a reduction furnace to make sulfur trioxide in the waste sulfuric acidsplit gas reacted with the gas sulphur to generate sulfur dioxide gas, organic matters, powdered carbon and the like in the waste sulfuric acid split gas generate sulfur dioxide, carbon dioxide, carbon monoxide, nitrogen, hydrogen chloride, water and the like, reduced furnace gas is subjected to complete combustion, waste heat recovery, purification and drying to obtain sulfur dioxide gas, part of the sulfur dioxide is liquefied to prepare a high-purity liquid sulfur dioxide product, and sulfur dioxide-containing gas which is not liquefied and the other part of the sulfur dioxide gas are mixed, and are subjected to conversion and absorption to prepare the concentrated sulfuric acid. Compared with the prior art, the method has the advantages that low temperature is used for conducting purification, concentration and regeneration resource utilization on the waste sulfuric acid to prepare high-quality liquid sulfur dioxide and concentrated sulfuric acid products, meanwhile, impurities ofthe organic matters, salt and the like in the waste sulfuric acid are subjected to proper harmless treatment, no secondary pollutants are generated, and resource recycling and environmental friendliness are achieved.