TaN/NbN multilayered coatings with nanoscale bilayer periods were synthesized at different Ar/N2 flow rates by RF (radio frequency) magnetron sputtering. XRD (X-ray diffraction) and Nano Indenter System were employed to investigate the influence of Ar/N2 flow rate (FAr:FN2) on microstructure and mechanical properties of the coatings. The low-angle XRD pattern indicated a well-defined composition modulation and layer structure of the multilayered coating. All multilayered coatings almost revealed higher hardness than the rule-of-mixtures value of monolithic TaN and NbN coatings. At FAr:FN2=10, the multilayered coating possessed desirable hardness, elastic modulus, internal stress, and fracture resistance, compared with ones synthesized at other Ar/N2 flow rates. The layered structure with strong mixture of TaN (110), (111), (200) and Nb2N (101)textures should be related to the enhanced mechanical properties.