Abstract: In order to figure out the field distributions inside nested frequency stirred reverberation chamber (RC), the field distributions in and out of the nested small RC are analyzed on the basis of the electromagnetic statistical theory. The size of the aperture connecting the two reverberation chambers is thought to be a key factor for the field distribution in the nested small RC. When the aperture is big enough for the electromagnetic wavelength, the field distributions should obey Rayleigh distribution; however, when it is very small, the situation will be similar with the vehicle-to-vehicle(V2V) communication, thus the field distribution in the small RC may follow double Rayleigh distribution. In order to examine the hypothesis of the distribution model, the scattering parameters S21 between the transmitting and receiving antenna are measured by a vector network analyzer in a nested RC, and the sample data are examined by the goodness of fit tests (KS tests). The test results prove the hypothesises, and this is helpful in understanding the test principle, and useful to improve the accuracy of the relevant test and expand the potential applications of frequency stirring nested reverberation chambers.