Abstract： By solving the RANS equations in conjunction with a RNG k-ε turbulence model, numerical simulation of the viscous flow around a KVLCC2 model appended with a rudder moving at different drift angles was conducted. The grid convergence study was performed using three sets of grid, and the computed and measured results were compared to show the reliability of the numerical method. Besides, the lateral force and yaw moment acting on the hull-rudder system moving at different drift angle, with and without rudder angle were calculated, and the numerical results were analyzed.