Abstract: Reduction of hydrodynamic vibration in the pump units of the fuel supply system is crucial for improving the reliability and service life of a Liquid propellant Rocket Engine (LRE). Pressure pulsations in the pump working path is the source of hydrodynamic vibration. It is useful to model pressure pulsations in the flow path and hydrodynamic vibration of the pump casing during the early stages of design. The study reports numerical modeling of three-dimensional non-stationary turbulent flow in a liquid-propellant axial screw booster pump unit. The spectral composition of pressure pulsations in the flowpath of the pump unit is analyzed. It is shown that the spectrum of pressure pulsations at the exit of the working screw impeller consists of tonal components at the Blade Passing Frequency (BPF) and its higher harmonics. At the entrance to the screw the spectrum of pressure pulsations is dominated by tonal components at the rotor frequency and BPF.