N-doped DLC films were deposited by RF-PECVD with N_2, CH4 as the source of reaction, Ar as dilution gas. The films" composition and microstructure were detected by FTIR, Ramn, XPS, XRD and SEM. Frictional behavior, hardness and elastic modulus of the film was also studied in various N_2 partial pressures.The result shows that N-doped DLC film can be prepared by RF-PECVD with N_2, CH4 and Ar as the source gas. The friction coefficient of the film decreased from 0.25 to 0.12 with the increase of N_2 partial pressure from 10% to 70%, which indicated that the film has a good wear ability, hardness and elastic modulus enhanced also. XRD spectroscopy shows that the N-doped DLC films are amorphous. SEM photo shows that N atoms were distributed in different layer of the film inside the web structure. FTIR spectra shows that most of N atoms existed in web structure as C=N bond, the other existences of N atoms are C=N and N-H bond, respectively. XPS spectra analysis indicated that the N content in films varied from 7.8% to 12.8% when the N_2 partial pressure increasing from 30% to 70%, which means the N/C ratio is directly proportional to N_2 partial pressure. In terms of the bond structure, the deconvolutions of XPS spectra show N accelerated sp~3 bond fraction of the film, which is corresponded to Raman analysis, in which sp~2/sp~3 ratio was decreased with the reduction of I(D)/I(G). At the end of thesis, we discussed the theory of the DLC growth and the mechanism of N improving DLC films" mechanical properties, in addition, the binding configurations of N inside DLC were also investigated.