In this study, the nanocomposite Ti-Si-N thin flims were prepared by reactive magnetron co-sputtering system. The Ti-Si-N film is a mixed composite consisting of the Ti-Si, Ti-N and Si-N compounds. The TiN phase is polycrystalline while SiNx is amorphous. As Si is added to the Ti-N compound to form Ti-Si-N, the microstructure becomes nanocrystalline grains embedded in an amorphous matrix i.e. nanocomposite quasiamorphous microstructure, which is also affected by the nitrogen flow ratio (FN2%) during co-sputtering. Therefore, the aim is to study the evolution of microstucture and mechanical properties of Ti-Si-N at different FN2%. The thickness, structure, morphology, chemical composition and mechanical properties of films were characterized by alpha-stepper profiler, Grazing Incidence X-ray Diffraction (GIXRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and nanoindenter, respectively. The experimental result shows that the deposition rate decreased with increasing N2 flow rate. According to Scherrer's formula, the grain size of films was below 5 nm. The surface morphology each film was very smooth due to fine grains. The maximum hardness was 21.5 GPa and H3/E*2 ratio was 0.321 at 7 FN% which was found at the transformation between polycrystalline and amorphous phases.