Diamond films were implanted with 50–110 keV N ions to the dosage of 1 × 1017 ions/cm2 at the temperature below 80°C. The possibility of the formation of C–N compounds in diamond films was investigated by means of X-ray photoelectron spectroscopy (XPS) scanning electron microscope (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared absorption spectroscopy (FTIR) and Raman spectroscopy. For the first time, the new evidence about the formation of plenty of C–N single bonds which is necessary for β-C3N4 formation in the diamond films has been presented. It is found that the low energy ion was suitable for the formation of C–N compound. The XPS analysis indicate that both C and N form three types of chemical states. FTIR and Raman spectra show that a large number of the C–N covalent bond have been formed. XRD and Raman analysis indicate that the structure of implanted layer is amorphous. The electrical resistivity in the implanted layer exhibits diamond-like property.