Propeller cavitation is the root cause for noise, hull vibration, as well as erosion on the propeller blades and appendages. Although it is a common practice for marine industry to predict the propeller cavitation by model tests, numerical simulation of propeller performance and the hull-propeller interaction has become feasible with the advancement of high performance computing. In this study, numerical studies of the flow field details around the ship hull with a rotating propeller are performed using Computational Fluid Dynamics (CFD) method by solving the unsteady Reynolds Averaged Navier-Stokes (RANS) equations. The numerical model is developed with commercial software package STAR-CCM+ for the cavitation prediction by considering the hull/propeller interactions and the free surface. Rotating propeller is modeled with an overset mesh, while κ-ω turbulence model is chosen instead of large eddy simulation (LES) or detached eddy simulation (DES) for higher computational efficiency while maintaining satisfied simulation accuracy. Cavitation bubble growth and collapse are estimated using Schnerr-Sauer cavitation model based on Rayleigh-Plesset equation. Simulation results suggest that the model developed in this study is capable to capture the flow field details under the effect of hull-propeller interactions and the free surface. This includes the cavitation emerging position, extinction position, as well as the cavitation patterns on the blade surface at various angular positions. The cavitation induced pressure oscillations on the hull at 1st to 3rd harmonics of Blade Passing Frequency (BPF) are also analyzed. The pressure fluctuation result can provide pressure load information for hull vibration evaluations in future.