With the development and application of blue semiconductor lasers, it has become a research hotspot to obtain high brightness blue light source by beam combining technology. In order to obtain high brightness blue light output, 48 single tube semiconductor lasers with wavelength of 450 nm and output power of 3.5 W are focused and coupled into 105 μm/0.22 NA fiber by fast slow axis collimation and spatial beam combination. The blue light with power of 144.7 W and brightness of 11 MW/(cm2?str) is obtained. The coupling efficiency is 93.78%, and the optical to optical conversion efficiency of the whole system is 86.13%.