Abstract: A series of LaCoO₃/MO₂ catalysts were prepared by support different carriers (M = Zr, Ti, Ce) through the citric acid sol-gel method, and the catalytic oxidation performance of toluene and NO and critical mechanism were investigated. The results found that the LaCoO₃/CeO₂ catalyst with CeO₂ as the carrier exhibited the best catalytic oxidation performance, the conversion rate of NO reached 68% at 300 ℃ and t₉₀ of toluene was 245 ℃. The physical and chemical properties and microstructure of the supported perovskite catalysts were characterized by BET, XRD, H₂-TPR, XPS technologies. The results showed that the supported perovskite had a larger specific surface area. Meanwhile, the supported perovskite catalyst had more active lattice oxygen and better redox performance. Moreover, the interaction between Co and Ce ions existed in the contact interface of LaCoO₃ and the carrier CeO₂, which was conducive to the formation of oxygen vacancies, thus providing more active sites for the reaction. The reaction mechanism was further explored by in-situ DRIFTs. NO oxidation on LaCoO₃/CeO₂ catalyst followed the Langmuir-Hinshelwood mechanism, and toluene oxidation followed the Mars-van Krevelen mechanism.