Abstract: The large-scale deep draft mooring ships are prone to drift and unmooring in complex flow environment, which affects the safety of port facilities and surrounding water domains. Aiming at a ship drifting and cable breaking accident at an offshore wharf, a large- and small-scale nested model of tidal current was established. The small-scale model was used to study the effect of flow regulation of different pile group arrangement schemes while its boundary condition of water level was provided by the large-scale model. The effect of ship and pile group on water flow was generalized by using the equivalent method of section and resistance. The nested model was validated using measured tidal and hydrological data. Then, the nested model was used to study the tidal current characteristics near the case project and the reasons of cable breakage, as well as the engineering effects of four pile group schemes. The results show that the optimal arrangement is 70° in the Axis direction and 150 m in the axis length. The implementation of this scheme generally decreased the tidal current velocity in the vicinity of the case project. Furthermore, the implementation of this scheme has no significant impact on the flow near the front of the adjacent wharf. Both results indicates that a good regulation effect has been achieved.