||Nowadays, nanotubes and nanowires have been in the focus of materials research due to their unique electronic and mechanical properties. The present study is focused on mechanical characterization of an individual nanotube or nanowire by the nano-bridge testing method with an atomic force microscope (AFM). Theoretically, a formula has been developed based on continuum mechanics with the consideration of the substrate deformation, the adhesion between the AFM tip and the nanowire (or nanotube), the adhesion between the nanowire (or nanotube) and the substrate. Afterwards, the influence of those factors in the evaluation of the Young's modulus of the nanobridge has been explored. Experimentally, we have conducted the nanobridge tests of individual silicon carbide nanowires and multi-walled carbon nanotubes on silicon templates (substrates). The experimental results indicate that the measured Young's modulus would be tens of percent smaller if we neglect the substrate deformation. Besides, a size-effect in Young's modulus is also found. Finally, molecular dynamics simulation has been employed to investigate the mechanical properties of silicon carbide nanowires as well as the size effect of those properties.