TiN/Ti multilayer films were deposited on Ti6Al4V substrate by alternatively depositing Ti layer and TiN layer in a reactive magnetron sputtering system, in order to explore the effects of modulation periods on microstructure and adhesion strength between films and substrate. The crystal structure, microstructure, hardness and adhesion strength between the films and the substrate were investigated by XRD, SEM, microhardness instrument and scratch test apparatus, respectively. The results show that all the TiN/Ti multilayer films contain three phases: Ti, TiN and Ti2N. SEM characterization shows that all the TiN/Ti multilayer films are column microstructure. For the films with high modulation period (5 layers), the interfaces between the Ti layer and the TiN layer can be clearly seen. With the decrease of the modulation period (increase of layer number), these interfaces gradually disappear. The microhardness of the TiN/Ti multilayer thin films is higher than that of the TiN single layer films. However, for the TiN/Ti multilayer thin films, with the increase of the number of layers, the microhardness slightly decreases. In addition, the adhesion strength of the TiN/Ti multilayer thin films with 30 layers is up to 73 N, which is much higher than that of the TiN single layer films.