In this work, TiN monolayer and TiN/TiAlN nanolayer coatings were deposited on 100C6 (AISI 52100) steel substrate by Physical vapor deposited (PVD) magnetron sputtering system. The morphological characterization was evaluated using an atomic force microscopy. The mechanical properties were determined by nanoindentation test. The adhesion was investigated by both microindentation and scratch test. The results show that the TiN/TiAlN nanolayer coating have the more rough surface and the better mechanical properties and adhesion compared to TiN monolayer coating. The effect of microstructural and mechanical proprieties on the adhesion behavior was further discussed. It was found that the improvement in adhesion of nanolayer system is in part due to the increase in plastic deformation resistance and the enhancement of mechanical properties (hardness and elastic modulus) and to the structure with a small grain size and a high number of interfaces.