The overall characterization method of waves using a single set of wave parameters has limitations when representing mixed waves accurately.By using multimodal characterization method to partition the wave spectrum into independent wave systems and representing each system in a parameterized form,mixed waves can be more accurately characterized.We investigate the influence of mixed waves condition characterization methods on water agitation in harbor through numerical simulation.We select three measured wave spectra of Chancay Harbor in Peru to theoretically reconstructed under different characterization methods,serving as input spectra for numerical models,and examine the typical errors introduced by the overall characterization method in describing mixed waves.The results show that wave conditions within the harbor are significantly impacted by the long swell system,and overestimation or underestimation of its energy levels leads to corresponding errors.Compared to the multimodal characterization method,the overall characterization method often yields average wave directions that do not align with reality,resulting in a misjudgment of the protective effect of breakwaters.