In the present study, numerical algorithms for a very large crude oil carrier(300K VLCC) were takeninto account. The potential flow analysis method was adopted to predict the flow pattern and the fluid forcearound a ship. The exact nonlinear free surface boundary condition were compared to predict the wavesystem generated by the ship and the trim and sinkage state of the ship also were considered. In order todeal with complex geometries of the 300K VLCC the panel cutting method was adopted to generate the shipsurface panel and the variable free surface panel method was taken applied to generate the free surface panel. The developed numerical analysis algorithm were applied to the 300K VLCC and the results predicted by thenumerical analysis were compared with the experimental data.