Based on the plane wave superposition model of the classical reverberation chamber, an improved plane wave superposition model is established in view of the fact that the existing probabilistic statistical model cannot simulate the environment of electromagnetic field with Rician distribution. In order to verify the validity of the model, the Probability Density Function(PDF) of the related electric field under different K factors is simulated by Monte Carlo method and fitted with ideal PDF. It is further verified that when the Rician K factor equals 0, the Rician distribution electromagnetic field model degenerates into a classical reverberation chamber field model. Finally, the influence of the sampling parameters(plane wave superposition number and agitator position number) on the simulation results is considered, and the best sample is determined to obtain stable PDF curve.