Stimulated Raman Scattering is one of the methods to shift the UV excimer laser radiation into the specific wavelengths in the near UV and visible regions. Diffraction limited first stokes output can be obtained by means of Raman beam cleanup. The effects of the beam quality of the injected emission on the Raman beam cleanup was investigated in this paper. The Raman gain coefficients and the saturated parameters of Raman amplifier were deduced for different H2 gas pressures.