The interfacial characteristics of CeO2/Si(100) with a nitrided layer were studied. The nitrided layer was formed by a process of nitrogen ion beam bombardment to the Si(100) substrate surface. Cerium oxide dielectric films were grown by pulsed laser deposition. The surface and structural characteristics of the nitrided layer were examined by atomic force microscopy, X-ray photoclectron spectroscopy. The interfacial structural characteristics and electrical properties of CeO2/Si(100) samples with and without the nitrided layer were analyzed by high-resolution transmission electron microscopy, current-voltage and capacitance-voltage measurements. The results show that the nitrided layer formed by nitrogen ion beam bombardment is a SiNxOy. layer. Such a SiNxOy. layer can effectively suppress the interfacial reactions between CeO2 and Si and is helpful to form a thinner and stable interfacial layer at the CeO2/Si(100) interface. Meanwhile, the nitrided interfacial layer is also to induce the reduced leakage current of CeO2/Si.