Conducting material shielding effectiveness testing in complex electromagnetic environments of reverberation chambers has become a key technology for accurately evaluating the electromagnetic protection ability of materials. To study the performance of the boundary deformation mutual coupling reverberation chamber shielding effectiveness testing system, experiments were conducted to verify the dynamic range, electric field distribution characteristics, and uncertainty. The results show that: in actual testing, a test result less than 60 dB is considered a reliable test value; the standard deviation of the electric field in both the transmitting and receiving reverberation chambers is less than 3 dB within the testing frequency range, fully meeting the uniformity requirements of the reverberation chamber; especially, the standard deviation of the spatial electric field in the receiving reverberation chamber is all less than 2 dB, and the uniformity is excellent; the expanded uncertainty of the testing system is 5.90 dB, which can be used as a material shielding effectiveness testing platform.