Abstract: In order to standardize and complete the radiated interference E-field threshold testing in reverberation chambers proposed previously, the influence factors on the measurement accuracy were analyzed in this paper, obtaining the error variation with different test conditions. It is revealed that the electrical size of the equipment under test (EUT) is the main restricted factor to the application range of the proposed method. Decreasing the electrical size of the EUT, an experiment was implemented to study the influence of the electrical size on measurement accuracy. The result shows that the measurement error can be decreased to less than 3 dB when the testing factors are reasonably chosen and the electrical size of the EUT is large enough. However, when the electrical size of the EUT is too small, the measurement uncertainty level may be larger than 3 dB. Accordingly, the proposed method is more proper for the EUTs with large electrical sizes.