The ensemble of the cavity scattering matrix and the corresponding radiation scattering matrix were computed, which were converted into normalized scattering matrix and normalized impedance matrix. Eigenvalues of the normalized scattering matrix were statistically analyzed by Dyson’s circular ensemble. The statistical independence of the magnitude and phase of the normalized eigenvalues were verified, and the phase is approximate to a uniform distribution, proving the existence of wavechaotic scattering in the cavity. There is a good agreement between the numerically determined marginal PDFs and those generated from random matrix theory.