Abstract: To meet the high impact resistance requirements for the power system of unmanned surface vehicle (USV) and to address the limitations in nonlinear stiffness of limiters and evaluation of time-domain impact responses for floating raft, an impact resistance evaluation study is carried out. The impact load is defined in accordance with the relevant naval standards, and a finite element model of the floating raft is developed using the time-domain simulation method, incorporating nonlinear stiffness model for the limiters. The dynamic responses are systematically analyzed under two conditions, with and without limiters, in terms of acceleration, displacement and stress. The results indicate that all performance indices satisfy the allowable impact resistance requirements. The limiters constraine the relative displacement of elastic components, and ensure the safety of shaft effectively. All associated parameter variations are within allowable limits. This study confirms the good impact resistance of the floating raft. The nonlinear model and evaluation methods enhance the engineering applicability of impact response predictions, and provide the simulation and evaluation framework for the impact-resistance design of power propulsion systems.