Thermal transport properties of nanowires are fundamental parameters for the thermal design of nanodevices, but their accurate determination is very challenging. Here, we present a reliable non-contact method for characterizing individual nanowires based on the analytical solutions of transient and steady-state thermal transport model. The thermal diffusivity can be extracted by comparing the temperature increases induced by continuous laser and square-pulse laser heating without knowing the laser absorption coefficient. Our method has been verified by comparing the measured thermal diffusivity of an individual 10.0 mu m diameter platinum wire with standard values. Then we applied this strategy to the characterization of an individual silicon nanowire (SiNW). Results show that SiNW's thermal diffusivity decreases from 6.3 x 10(-5)m(2)/s to 2.6 x 10(-5) m(2)/s when the temperature increases from 270 K to 485 K, which is lower than that of the corresponding pure bulk silicon value, indicating the surface and impurity scattering reduces the mean free path of the heat carriers. (C) 2019 Elsevier Ltd. All rights reserved.