AbstractRoll damping test is used to calculate roll damping coefficient, which is an important coefficient in predicting ship seakeeping capability. And because of the complexity of naval ship's shape (with bulbous bow and transom stern), it's rare to find the numerical simulation of its roll damping motion. In this paper, DTMB5512 model's roll damping motions at different initial roll angles are simulated based on CFD, vessel's roll damping coefficients are calculated through the simulation results, and the results show good agreements with the tank test data.