In order to improve the denitration performance of La-Mn perovskite catalyst, a series of Ce modified perovskite La-Mn composite oxide catalysts were synthesized by citric acid sol-gel method. The structure, morphology, composition and surface physicochemical properties of the catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), N2 adsorption-desorption (BET) and temperature programmed technology (H2-TPR/NH3-TPD).The results of the activity test showed that the denitration performance of Ce modified perovskite type La-Mn composite oxide catalysts are improved. When the Ce/Mn molar ratio is 0.2, the catalyst has the best denitration activity. The NOx conversion rate could reach 90% at 135 ℃, and maintaining more than 90% NOx conversion in the temperature window range of 135～260℃. XRD results showed that the perovskite type La-Mn composite oxide modified by Ce has porous structure and could maintain the perovskite structure of LaMnO3.15. However, Ce ions do not completely enter the perovskite structure, and some of them cover the catalyst surface in the form of oxides. At the same time, part of Mn ions in the lattice overflow from the perovskite structure in the form of Mn3O4, thus maintaining the structural stability and charge balance. SEM and BET results showed that the specific surface area of the catalyst increases and more active sites are provided after the introduction of Ce, which promotes the denitration reaction. XPS results showed that Ce modified catalyst produces more Mn4+ and chemically adsorbed oxygen, which promotes the oxidation of NO. The results of temperature programmed technology showed that the catalyst modified by Ce has better redox performance and more acidic sites, which is conducive to the denitration reaction. Therefore, Ce modified La-Mn composite oxide could improve the denitration performance by promoting NO oxidation and NH3 adsorption.