The paper discusses computer modeling of the temperature dependences of the dielectric constant of polymer composite materials. Issues of the combined radio wave and thermal methods of diagnostics of nondestructive inspection of the polymer composite materials in the laboratory conditions are considered. The paper offers a method for combining the measurement and heating processes. This method can be implemented, the way is to do the heating and the measurement at the same frequency with using a high-power sounding wave. As a result, the radiant material heating is obtained, and we judge about the substance parameters and a presence of defects in the substance by a reflected wave in an indirect method. A descriptive characteristic of such a problem boils down to describing all the processes in the sample by the electrodynamic theory. The heating process can also be described by the electrodynamics equations, but the process will be described by the thermal equations in the nonstationary heating conditions in the most accurate way.