The influence of boundary deformation on the resonant frequency drift of a reverberation chamber was analyzed, and a design of a reverberation chamber reflector with controllable boundary deformation was proposed. Transforming the traditional mechanical stirrer into a wrinkled wall, the goal is to change the boundary conditions by controlling the angle between adjacent reflection modules. A simulation model of a 5 m×4 m×3 m reverberation chamber was constructed, and the effectiveness of the controllable boundary deformation reverberation chamber was analyzed from three aspects: field uniformity, stirring efficiency, and field distribution. The results show that the standard deviation of the electric field in the test area was less than 3 dB, the stirring efficiency was higher than that of traditional mechanical mixers, and the electric field in the test area followed the ideal distribution pattern of the reverberation chamber. This method can effectively increase the testing area space of the reverberation chamber.