Using the calculation way suggested by P. H. Hu et al. We solve the zeroth –order equations suggested by A. Flusberg et al in numerical method. We calculate the Stokes intensity, the pump intensity, and the fidelity that vary with the positions in the Brillouin cell, and obtain the transverse distributions for the Stokes phase and intensity at several positions in the Brillouin cell, and calculate the reflectivety and fidelity at the pump entrance that vary with the gain G =gIp0L.