Abstract: Diamond like carbon (DLC) films broadly serve as the anti-wear protection coatings of cutting tools, moulds and so on. However the problem of the adhesion strength of the DLC films and their substrates at the interfaces block their applications in practice. The adhesion can be improved by adding a titanium carbide transition layer (TiC) between the i-C amorphous coating (ion-assisted carbon film)and the steel-based substrate. The test of the SEM (scanning electron microscope) and the EPMA (electron beam probe microanalysis) show improvements of the adhesion strength at the interface of the mid-layer (TiC) and the i-C as well as at the interface of the mid-layer and the substrate. The measurement of the scratch tester provides another evidence of this improvement of the adhesion strength. The macrocosmic tests of the film's mechanical properties show that these composite films retain good performances of the DLC films, such as very high hardness and a very low friction coefficient.