In order to improve the computation efficiency of floating transportation drag of the caisson and immersed canal either in static water or in current and waves, a few CFD methods such as the double model method, VOF method including steady and unsteady methods, and numerical wave generation method were studied based on general CFD codes StarCCM+ and FLUENT and further development of FLUENT, which were used to discuss the effects of wave, current, free surface and inflow angle on the floating transportation drag. It is shown that for immersed canal in static water, the free surface can be neglected, while for caisson it cannot; for caisson with inner concavity, unsteady VOF method is necessary since steady method can conceal the sloshing of inner fluid due to the initial velocity.