Rapid increment is achieved on the capacity and quantity of floating offshore wind turbines (FOWTs) in the past decades. Meanwhile, a rising hazard from ship collisions has been identified and this could lead to severe economy loss and human injuries. Numerical modelling for the ship-FOWT collision analysis has been challenging in considering the internal dynamics and external dynamics with hydro-aero effects simultaneously. This paper discusses the influences on energy dissipation during ship-FOWT collision resulted from different numerical modelling methods. LS-DYNA codes are employed to simulate the ship-FOWT collision in the study. The hydrodynamic effects are considered by using constant added mass and a one-way coupling method, respectively. The coupling method employes the user-defined subroutine in LS-DYNA to update hydrodynamic and mooring forces during collision. The hydrodynamic loads are calculated based on potential-flow theory while the mooring forces are simplified as linear restoring forces. The influence on energy dissipation and structural response from structural flexibility of tower was also studied. The rotor-nacelle assembly (RNA) is not modelled in detail and they are represented as a lumped mass with equivalent mass and inertia properties. Several collision scenarios are then simulated and the energy dissipation, collision force, and other structural responses from different modelling approaches are investigated and compared. It is found that for low-speed impact, both methods can give consistent predictions but the CAM model could lose the capacity when collision velocity is high. The research outcomes can provide a basic view for energy absorption mechanisms in ship-FOWT collision and can serve as benchmarks for futural development of analytical method.