We have experimentally studied the Brillouin-Rayleigh scat tering in dispersion compensation fibers under Raman pump of different po we rs, and analyzed the characteristics of output spectra and the variation of th e spectra with pump power in detail. Then, based on the known theoretical model of the first-order stimulated Brillouin scattering, we deduce the theoretica l model for multi-order Brillouin-Rayleigh scattering. By this model, we have ma de numerical simulation, and the results show that theory and experiment are consiste nt at lower pump power, but have great differences at higher pump power.Moreove r, we analyze carefully the differences between theory and experiment. Finally,from theoretical calculation and experimental results, we obtain the saturation charac teristics of Brillouin-Rayleigh scattering at higher pump power, so that we can easily explain the cause of flat multi-order Brillouin-Rayleigh scattering at a certain higher Raman pump power.