Rather than using conventional low-temperature plasma, the pulsed high-temperature plasma was used to synthesize C-N films. CH4 + N-2 mixture was used as the gas source. The effect of substrate temperature on the deposition was studied. It was found that with the increase of substrate temperature, the deposition rate dropped drastically, the content of H in the films decreased and the hardness of the films was improved; The N/C ratio, however, changed only by a small degree, suggesting that the C and N has been well combined by using high-temperature plasma.