In this article, the thermoelastic interactions in an isotropic and homogeneous semi-infinite medium with variable thermal conductivity caused by an ultra-short pulsed laser heating based on the linear nonlocal theory of elasticity has been considered. We consider that the thermal conductivity of the material is dependent on the temperature. The surface of the surrounding plane of the medium is heated by an ultra-short pulse laser. Basic equations are solved along with the corresponding boundary conditions numerically by means of the Laplace transform technique. The influences of the rise time of the laser pulse, as well as the nonlocal parameter on thermoelastic wave propagation in the medium, have also been investigated in detail. Presented numerical results, graphs and discussions in this work lead to some important deductions. The results obtained here will be useful for researchers in nonlocal material science, low-temperature physicists, new materials designers, as well as to those who are working on the development of the theory of nonlocal thermoelasticity.