Abstract: Objectives As an anisotropic material, composite materials offer significant design flexibility. However, the structural complexity of pump-jet propellers, combined with fluid-structure interaction effects, leads to substantial deformation of composite rotors under hydrodynamic loads. This complicates the evaluation of structural deformation, stress-strain behavior, and hydrodynamic performance. This study builds upon existing hydrodynamic performance data for metallic pump-jet propellers and progressively investigates the influence of composite material application on the performance of composite rotor pump-jets. Further analysis is conducted on structural deformation, stress-strain response, and hydrodynamic characteristics. Additionally, through pre-deformation optimization design, the hydrodynamic performance of the composite pump-jet is restored while preserving the inherent advantages of composite materials.Methods A composite pump-jet propeller with a diameter of 0.2375 m was selected as the research subject. Based on a fluid-structure interaction iterative algorithm for composite pump-jet propellers, Carbon/Resin matrix was used as the layup material. Layup designs were performed for composite rotor pump-jets at ply angles of -30°, -20°, -10°, 0°, 10°, 20°, and 30°. Two-way fluid-structure coupling numerical simulations were carried out to evaluate structural deformation, stress-strain distribution, and hydrodynamic performance of the rotor blades. Subsequently, a pre-deformation design was applied to restore the hydrodynamic performance of the composite rotor pump-jet.Results Numerical results indicate that metallic pump-jet propellers undergo minor deformation under fluid-structure interaction, whereas composite rotor pump-jets exhibit varying degrees of deformation depending on the ply angle. For ply angles between -30° and 0°, the composite rotor deforms in the direction of reduced pitch angle; for angles between 0° and 30°, it deforms toward an increased pitch angle. At a ply angle of 0°, the change in pitch angle is minimal compared to that of the metallic rotor, resulting in hydrodynamic performance closely matching that of the metallic counterpart. Analysis of pitch angle variations along the blade radius revealed that the maximum deformation of the composite rotor consistently occurs near the blade tip. After pre-deformation optimization, the hydrodynamic performance of the composite rotor was restored to within 3% of that of the metallic pump-jet, achieving the intended recovery objective.Conclusions The findings provide valuable insights for the structural design of composite rotor pump-jets and contribute to the improvement of their hydrodynamic performance.