In order to enable the fiber laser to efficiently pump and generate high power laser, the pump source is typically coupled into the active doped fiber through a duplet lens system. For there are some disadvantages of duplet lens system, it can be replaced by a compound parabolic concentrator to improve the pumping efficiency and simplify the coupling system. The compound parabolic concentrator can concentrate all the lights with incident angles less than its maximum acceptance angle to its exit surface, and most of the energy is concentrated within the active doped fiber’s acceptance angle, so it has high coupling efficiency. In addition, the compound parabolic concentrator has the advantages of simple structure, small size, and simple docking with the pump source. Simulation proves that the compound parabolic concentrator has higher coupling efficiency than the duplet lens system, which is very suitable for the pump source injection test of fiber laser and can provide conditions for generating high power laser.