Large-eddy simulation is performed to study the turbulence statistics and flow structures of the water past a rotating axial-flow pump under different flow-rate working conditions. A novel sharp-interface level-set based immersed boundary method is applied to capture the complex geometry of the pump. An unstructured triangular mesh is used to discretize the complex surface geometry of the pump, and a ray-tracing method is employed to classify the computational domain into fluid and solid regions. Turbulence statistics, including the mean velocity, turbulent kinetic energy (TKE), turbulence production, and turbulence dissipation, are analyzed under five different flow-rate working conditions around the designed condition. The results show that unsteady wake, tip leakage flow, and flow separation are accompanied by a high TKE magnitude. For the high turbulence intensity under off-designed working conditions, the tip leakage flow plays a leading role at low flow-rates, and flow separation dominates at high flow-rates. (c) 2021 Elsevier Ltd. All rights reserved.