To address the inaccuracy in predicting the motion responses of moored ships caused by the traditional overall wave representation method,which neglects the bimodal spectral characteristics of mixed waves,this study investigates the motion response characteristics of moored ships based on the multimodal wave representation method.Numerical simulations are performed,with field-measured wave data from Chancay Bay,Peru,as input.Three representative mixed wave spectra are reconstructed to systematically analyze the differences in the simulated results of moored ship response characteristics between the overall and the multimodal wave representation method.The results indicate that the overall method oversimplifies wave energy distribution.In conditions dominated by short waves,this approach artificially concentrates wave energy,resulting in an overestimation of the calculated motion response.Conversely,in scenarios involving long-period swells,the multimodal wave representation method can accurately isolate the long-wave components causing low-frequency resonance of the moored ship,effectively avoiding underestimation risks.The multimodal wave representation method can more accurately capture the hydrodynamic impact of mixed waves on mooring systems.Thus,it is recommended to replace the traditional overall representation method with it in engineering designs for complex sea states to enhance safety margins.