The ensemble of the cavity scattering matrix and the corresponding radiation scattering matrix were obtained within the computer-box cavity. For a given Loss-Case cavity，normalized impedance and normalized admittance were obtained by random matrix theory. Dyson’s circular ensemble proved the existence of wave-chaotic in the cavity. The good agreements between the experimentally observed values and the Random Matrix Theory results were achieved for the normalized impedance, which indicated the prediction function of random matrix theory on wave chaotic systems. There was a good agreement between the statistic properties of normalized impedance and normalized admittance obtained in experiments，which testified that these two physical quantities were unaffected by the coupling of systems.