The amorphous/polycrystalline Si3N4/CrN and Si3N4/TiN nano-structured multilayer films have been fabricated by RF reactive magnetron sputtering. The microstructure and properties of these films were measured by XRD, HRTEM and nano-indenter There is no superhardness effect in the Si3N4/CrN multilayers. The hardness values of Si3N4/CrN multilayers are between those of the constituent CrN and Si3N4 films at a substrate temperature of 20∼C, and are a little higher than those of Si3N4 films at a deposition temperature of 500°C. However, the superhardness effect was found in Si3N4/ TiN multilayers. The hardness of Si3N4/ TiN multilayers is affected not only by modulation periods, but also by layer thickness ratio and deposition temperature. The maximum hardness value is about 40% higher than the value calculated from the rule of mixtures at a deposition temperature of 500°C and a layer thickness ratio (l Si3N4/ l TiN) of 3 / 1. Based on experimental results, the hardening mechanisms in these multilayers have been discussed.