For the requirement of high power slab laser system′s beam shaping,one-dimensional beam shaping system is simulated by CODE V software,optical transfer function of beam shaping direction of the output light is close to the diffraction limit. When the beam shaping field is 0.5 mrad,the wave aberration is 0.105λ. He-Ne light and fiber seed light wavefront after shaping are measured by using four wave shear interferometer,P-V value changes less than 0.25λ,RMS value changes less than 0.05λ.