Under the experimental condition of loading in isothermal process, the microwave radiation energy of solid matters like concrete varied with the change of pressure. Experiments were carried out considering two polarized states (horizontal and vertical) of 3 wave bands including 2cm, 3cm, and 10cm. The experiments demonstrated that mechanical energy can directly excite rotation state energy level jump of solid matters (rocks and concrete, etc.) molecules without need of intermediate physical process of heat generating. This phenomenon directly connects stress with microwave radiation energy physically. This paper puts forward experimental basis and lays physical foundation for the remote measurement of stressfield distribution and evolvement of large concrete engineering by passive microwave remote sensing, and for rock engineering’s stability monitoring and stability-failure predicting.