Developing a catalyst with high SO₂ and H₂O resistance to achieve high-performance CO oxidation for specific industrial applications is highly desirable. Here, three catalysts were prepared using cerium titanium composite oxide (CeTi), molybdophosphate with Keggin structure-modified CeTi (Keg-CeTi), and molybdophosphate without Keggin structure-modified CeTi (MoP-CeTi) as supports, and their sulfur and water resistance in CO oxidation were tested. The characterization of XRD, BET, SO₂/H₂O-DRIFTS, XPS, TEM, SEM, NH₃/SO₂-TPD, H₂-TPR, and ICP techniques revealed that the high SO₂ and H₂O resistance of Pt/Keg-CeTi in CO oxidation was related to its stronger surface acidity, better reduction of surface cerium and molybdenum species, and lower SO₂ adsorption and transformation compared to Pt/CeTi and Pt/MoP-CeTi.