Abstract: An analytical method is developed for the thermo-hydro-mechanical responses of a semi-infinite saturated porous medium subjected to one-dimensional harmonic thermal loading. The expressions for temperature, pore pressure and displacement fields are deduced. The processes of temperature responses from instantaneous state to quasi-steady state are discussed. The fluctuation characteristics of temperature, pore pressure and displacement in quasi-steady state are analyzed. The studies show that the thermal mechanical response is gradually conducted from the surface to deep layer with elapsed time, and finally reaches a quasi-steady state. The amplitudes of the thermal responses decrease with increasing depth; however, the corresponding phases are delayed. The pore pressure distributions with depth become more uniform with increasing permeability. When the depth is greater than a wavelength, the values of thermal responses approach zero.