Abstract: During external characteristic experiments of centrifugal pumps conveying fiber suspensions with varying concentrations, it was observed that the 0.2% concentration fiber suspension exhibited universal applicability in pump efficiency enhancement, demonstrating efficiency improvement across all flow-rate conditions. In contrast, the 0.6% concentration suspension only improved pump efficiency under high-flow-rate conditions. To elucidate this phenomenon from a microscopic perspective, MATLAB-based image recognition techniques were employed to statistically analyze the orientation angles of fibrous particles within the CFD-DEM （computational fluid dynamics-discrete element method）coupled flow field. The results revealed distinct orientation trends in fiber distribution: low-concentration suspensions exhibited fibers predominantly aligned with the fluid flow direction, characterized by higher orientation stability, smaller orientation angle variations, and a higher proportion of high-velocity particle clusters.