Diamond-liked carbon (DLC) film is an important material and has many application in industry. Recently doping impurity into the DLC to change the properties of DLC thin film is a research topic attracted scientists. In this thesis, DLC films were deposited by plasma-enhanced chemical vapor deposition (PECVD) on the Si wafer and glass. Acetylene was used as the source of carbon, and nitrogen was doped in DLC need too dopants of grow N2 and NH3. The growth mechanism and differences of the nitrogen doped DLC films were studied by methods of NK measurement, SEM and nano indentation. The analysis of nano indentation showed that the hardness and Young¡¦s Module decreased with increasing N2 flow rate. However, for increased NH3 a flow rate, the hardness and Young¡¦s Module of DLC were increased. The characteristic peaks of nitrogen doped DLC in the FTIR transmittance spectra were studied, sp2 C=H bond(2945 cm-1), sp3 C-H bond(2910 cm-1), and also the C¡ÝN (2200cm-1)and C=N bond(1625cm-1) are observed in DLC. The results of FTIR shows nitrogen was doped into DLC successfully. The DLC thin films thickness was determined by the NK analysis, and it is found the deposition rate of DLC was increased with the increasing flow rate of N2. However, for increased NH3 flow rate, the DLC deposition rate was decreased. From SEM, micrographs the NH3 doped DLC yielded rough morphology. The surface of N2 doped DLC thin film, revealed smoother. A growth mechanism of diamond with different dopant was proposed and explained the properties of DLC thin film with different deposition condition.When N2 was used as dopant source, the N2+ ions were induced by plasma and attracted upward due to the RF self-bias voltage. Therefore ,the surface of thin film was not bombarded due to N2+ ions. On contrast, when the NH3 was used as dopant source, the NH2- ions were produced and distracted downward by the RF self-bias voltage. And then the surface of the thin film was etched by the NH2- ions. Form the XPS analysis, the composition of sp3 C-C(285.4 eV) and sp3 C-N (287.7 eV)were decreased with increased N2 flow rate.However, the composition of sp3 C-C and SP3 C-N were increased with decreasing the NH3 flow rate. The composition of nitrogen in the DLC film increased with higher N2 flow rate. The number of sp2 bond was increased and the hardness was decreased with higher amount of nitrogen in the DLC film. This result is consistent with the nano indentation,FTIR analysis and explained by the ionic transportation growth mechanism model.