In order to develop a concentrator system suitable for solar-pumped fiber lasers, an improved compound parabolic concentrator (CPC) for fiber coupling was proposed based on the analysis of the feasibility and defects of traditional CPC for fiber coupling. A solar pumped multistage concentrator scheme consisting of a primary parabolic mirror and a secondary improved CPC has been developed, and comparison with the scheme of a secondary concentrator composed of a general CPC and a lens group, as well as the scheme without secondary concentrators, has also been carried out. The simulation results of ray tracing show that the improved CPC can overcome the divergence of ordinary CPC outgoing light,thereby improving its coupling efficiency with optical fiber.When the receiving angle range of the primary mirror is within ±0.55°, the coupling efficiency of the improved CPC with optical fiber is maintained at 93.53%-96.43%, which is superior to other schemes.