Abstract: In order to fully understand the internal flow characteristics of tubular pumps under operating conditions, the turbulent flow of a tubular pump under the designed condition simulated by computational fluid dynamics（CFD） technology and immersed boundary method based large-eddy si-mulation（IBM-LES） was studied. The simulation was based on 3 D Cartesian grid system, the Navier-Stokes equations were discretized by a finite difference method in space and advanced in time using a second-order Runge-Kutta method. The LES was applied with dynamic Smagorinsky model. Boundaries of solid parts were described by level set function. The result shows that the turbulence kinetic energy（TKE） is weak on the circumferential section across the root of impeller blades. The highest TKE is located at the wake of rotating impeller blades on the midspan section and the component in streamwise direction contributes most of the TKE. The TKE near the tip clearance of impeller blade is strong and contributed by components in three directions evenly. At the wake of outlet guide vanes, the turbulence dissipates and developes along the streamwise distance, the wake tends to exhibit the characteristics of pipe uniform flow. The results provide theoretical supports and engineering operation references for stability improvement of tubular pumps.