To improve the brightness of semiconductor lasers as the pump sources of fiber lasers and solid lasers, based on the technologies such as beam collimation, spatial beam synthesis, synthesis of polarized light, and optical fiber coupling, a compact beam shaping system that uniforms beam quality of fast and slow axes of semiconductor lasers is proposed. Using similar stepped prisms and two 30° rectangular prisms to fill the dark region in fast axis direction and a polarization beam combiner to compress the slow axis beam width, a compact and high brightness fiber coupling system is designed. The system is composed of eight mini-bars, which are coupled into an optical fiber with a core diameter of 100 μm and a numerical aperture of 0.22. The output power is 272.4 W, the optical conversion efficiency is 85.1%, and the maximum brightness is 22.832 MW/(cm²·sr).