Abstract: Aiming at the SO₂ up-to-standard emission in tail gas of sulfur recovery unit, a new SO₂ ultra low emission technology was developed. By using Ti-based catalyst CT6-8 with excellent hydrolysis performance in Claus reactors, the new type low temperature organic sulfur hydrolysis catalyst CT6-11 in tail gas hydrogenation reactor, and H₂S deep removal solvent CT8-26 in hydrogenation tail gas desulfurization system, the SO₂ mass concentration in tail gas was decreased significantly. The technology was successfully applied in Tahe Refinery Company and Zhongjin Petrochemical Company, and the SO₂ mass concentration was reduced to 50 mg/m³ and 31 mg/m³ or lower respectively.