Doppler spectrum is the frequency-domain performance of the time-varying characteristics of the channel. In order to study the time-varying characteristics of the channel in the reverberation chamber, an approximate model of Doppler spectrum in the reverberation chamber is built by analyzing the scattering mechanism and the distribution of scatters, and experiments are designed to validate the model. The experimental results show that the model can describe the Doppler spectrum in the reverberation chamber, and the electromagnetic environment with certain Doppler spread can be synthesized in the reverberation chamber by selecting the appropriate stirring velocity and carrier frequency, which is of great significance for describing and controlling the time-varying characteristics of the channel in the reverberation chamber.