The effect of adhesion and electronic structure of TiN(111)/DLC interface is studied by the first-principles plane wave pseudopotential method within the density functional theory, and the inherent properties of the TiN transition layer to improve the adhesion performance of the metal substrate and DLC film were clarified. According to different surface terminations (Ti terminations and N terminations) of TiN(111) and the atomic coordination types of the interface (top, center and hollow), six possible interfaces models of TiN(111)/DLC have been constructed and calculated. The results show that Ti-center interface has the maximum adhesion energy；When TiN is terminated by N atom, the N-top interface is the most stable interface model, and the relaxed adhesion energy is 8.281 J/m_². The calculation results of the electron density, the partial density of states and Mulliken overlap population all suggest that Ti-C bond formed at Ti-center interface contains covalent and ionic properties, while N atom and C atom at N-top interface are mainly C-N covalent bond. In contrast, the N-top model is more likely to appear in the TiN/DLC interface.