The surface properties of the modified rare earth concentrate supported by γ-Al2O3 and the factors affecting the catalytic activity were studied. Roasting and NaHCO3-oxalic acid leaching were used to study on surface properties of modified rare earth concentrates. The effects of modification treatment on the microstructure and catalytic activity of the impurity-removed samples were characterized by XRD, BET, TPD, TPR, XPS, in-situ DRIFTS. The results show that the optimum nitrogen removal efficiency of the modified rare earth concentrate loaded γ-Al2O3 sample can reach 80.5%. For rare earth concentrates, the oxalic acid and the mineral are co-calcined together, and then leached by a NaHCO3, the content of calcium fluorophosphate and calcium fluoride is remarkably small, and the content of Ce7O12 in the active powder is increased and the dispersion is more uniform. Active ingredients on the sample surface such as Ce, La, Mn were increased, the specific surface area of the sample was increased. The redox capacity of the rare earth concentrate surface and the NH3 adsorption performance are enhanced. Ce coexists in the form of Ce3+ and Ce4+. Mn coexists in the form of Mn3+ and Mn4+. The synergistic action of cerium and manganese increases catalytic activity.