The invention relates to a method for reducing the SO2 (sulfur dioxide) emission concentration of a sulfur device. The method comprises a thermal reaction unit, a catalytic reaction unit and a tail gas purification unit, wherein in the thermal reaction unit, an acid gas containing hydrogen sulfide is thermally transformed into the element sulfur and a process gas; the element sulfur is fed into a liquid sulfur tank to obtain liquid sulfur, while the process gas is fed into the catalytic reaction unit; Claus tail gas generated from the process gas in the catalytic reaction unit enters the tail gas purification unit; the Claus tail gas is subjected to hydrogenation, chilling and amine liquid absorption; one part of the purified tail gas is used as a gas stripping gas for bubbling degassing of the liquid sulfur in the liquid sulfur tank; the liquid sulfur degassed tail gas further is mixed with the Claus tail gas and then treated in a hydrogenation reactor; after hydrogenation, the mixed tail gas is chilled, purified through amine absorption, burnt and discharged. The method provided by the invention is capable of removing the purified tail gas hydrogen sulfide below 10ppm(v); the flue gas SO2 emission concentration of the sulfur device can be reduced below 100mg/m<3>, so that the new environmental protection standards which are about to be executed are satisfied.