Abstract: Aiming at the difficulty of the up-to-standard emission for tail gas of existing sulfur recovery unit, the new desulfurization technology developed by Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gasfield Company was used in sulfur recovery unit of Tahe Refining & Chemical Co., Ltd. The replacing catalysts and solvent have higher organic sulfur hydrolysis ability and higher H₂S removal efficiency respectively. Assisted by the adjustment of local process parameters, the goal of SO₂ mass concentration in discharged tail gas less than 100 mg/m³ was achieved. The application of the technology could decrease the investments of the unit and simplify the operation. The reliability was confirmed and it could provide a reference to reach standard for the tail gas discharge of similar unit.