Aiming at the problem of catalytic oxidation of CO by Pt /TiO₂ in sulfur-containing sintering flue gas，selenium ( Se) doping modification is used to improve its sulfur resistance. The reasons for Se-doping to enhance the sulfur resistance of Pt /TiO₂ catalyst ( PSeT) are studied by means of fixed bed sulfur resistance toxicity test，pore structure analysis，XRD，XPS and SO₂-TPD. The results show that the Pt /TiO₂ catalyst ( PSe_{0. 10}T) doped with 0. 1% Se has the best sulfur resistance performance. When 798 mg /m³ SO₂ is introduced at 200 ℃，the catalytic efficiency decreases slightly from 100% ，and the removal rate is still greater than 80% after a long-term test of 12 h. After removing SO₂ the catalytic efficiency gradually recovers to 100% ; after SO₂ poisoning，the N₂ adsorption amount and specific surface area of the PSe_{0. 10}T catalyst decrease slightly，and the sulfate deposition inhibition effect is obvious; after SO₂ poisoning，no new phase is found in the XRD test results，and the XPS test results show that the S content on the surface of the PSe_{0. 10}T catalyst is the lowest，and the sulfurization product is TiOSO₄ ; SO₂ TPD analysis shows that the PSe_{0. 10} T catalyst has weak SO₂ adsorption and a low sulfate decomposition temperature，showing good sulfur resistance performance. The results can provide a theoretical basis for the development of high-performance sulfur resistance CO oxidation catalyst.