In the present work, nanocrystalline Ti/Cu multilayer thin films were fabricated using direct current magnetron sputtering with different layer thicknesses, namely 250, 100, 50, 25 and 5 nm. In addition, a group of thin films were prepared with various multiple modulation ratios where each bilayer was set to be equally 100 nm. The size-dependent deformation behaviour of the films was studied using the nano-indentation and nano-scratching techniques. The results showed that the flow strength of the films tended to increase as the layer thickness decreased. Moreover, the strength and scratch resistance of the films can be further optimized by tailoring the thicknesses of the two adjacent layers, while the thickness of each bilayer remains unchanged. The size-dependent strengthening mechanism is discussed with respect to microscopic observations.