The composite support CeZrYLa+LaAl was prepared by a co-precipitation method, and Pt-Rh bimetallic catalysts were fabricated on this support using different preparation procedures. The catalytic activities of these materials were tested in a gas mixture simulating the exhaust from a stoichiometric natural gas vehicle. The as-prepared catalysts were also characterized by X-ray photoelectron spectroscopy, X-ray diffraction, N2 adsorption-desorption and H2-temperature-programmed reduction. It was found that the order of activities for CH4, CO and NO conversion was Cat3 ≈ Cat2 > Cat1, where Cat3 had the lowest light-off temperature (T50) for CO (114 ℃) and NO (149 ℃), the lowest complete conversion temperature (T90) for CH4 (398 ℃) and CO (179 ℃), and the lowest ΔT (T90-T50) for CH4 (34 ℃) and CO (65 ℃). Cat2 showed the lowest T50 for CH4 (342 ℃), the lowest T90 for NO (174 ℃), and the lowest ΔT for NO (17 ℃). Cat1 had the highest T50 and T90 and the largest ΔT out of all three catalysts. Indicating that Pt-Rh bimetallic catalysts (Cat2 and Cat3) prepared by physically mixing Pt and Rh powders exhibited much better catalytic activity than those (Cat1) prepared by co-impregnation, since homogeneous Pt and Rh sites made a significant contribution to CH4/CO/NO conversions. In contrast, strong Pt-Rh interactions in the co-impregnation materials affected the oxidation states of Pt, and the Pt-enriched surface blocked active Rh sites. Moreover, Cat3 was prepared by adding additives (La3+, Zr4+ and Ba2+) into the physically mixed Pt-Rh catalysts. XRD results demonstrated that the additive cation (Zr4+) was incorporated into the CeO2-ZrO2 lattice, thus creating a higher concentration of defects and improving the O2-mobility. XPS results showed that the Cat3 had the highest Ce3+/Ce ratio, suggesting the presence of a significant quantity of oxygen vacancies and cerium in the Ce3+ state. All of these further promoted the three-way catalytic activity and widened the air-to-fuel working-window.