Rare earth nitriding was considered as an effective method to accelerate the nitriding efficiency. However the catalytic mechanism was not clear due to the uncertainty of rare earth (RE) elements' existence during nitriding. In the present work, the LaFeO3 perovskite oxide was attempted to use as a catalyst in the gas nitriding for the first time. The effect of nitriding temperature on the microstructure and properties of the RE nitrided layer was investigated and the catalytic mechanism of the RE was discussed. The microstructure, phase composition and microhardness profiles of nitrided layers were characterized by the optical microscope, X-ray diffraction and micro-hardness tester, respectively. The corrosion resistance of nitrided layers was tested by the potentiodynamic polarization technique. Pin-on-disc tribometer were applied to evaluate the wear property. The X-ray photoelectron spectroscopy and scanning electron microscope equipped with an energy dispersive X-ray spectroscopy were used to identify the catalytic mechanism of the RE by analyzing the chemical state and elemental distribution on the nitrided surface. The results show that a perovskite-type oxide, LaFeO3, would form after the gas nitriding, which presents an obvious catalytic activity and increases the thickness of nitrided layers. In addition, the mechanical and corrosion properties could also be improved after nitriding with RE addition. The LaFeO3 perovskite oxide could accelerate the nitriding rate by adjusting the ratio of the adsorbed nitrogen (N) and dissolved N. On the other hand, the sufficient oxygen vacancies in the LaFeO3 oxide could provide more diffusion routes for N atoms.