Abstract: Objectives To investigate the dynamic elastic-plastic response characteristics of ships with large openings in the middle in waves.. Methods Referring to the characteristics of cargo loading and large openings in the middle of container ships, a stiffened plate ship model is designed and manufactured. A series of linear and nonlinear operating conditions tests are conducted in a wave making pool to measure the elastic and plastic deformation of the ship model under the combined action of ballast and waves, as well as the stress changes in the deck area. Results The results indicate that the appearance of structural plasticity slightly reduces the growth amplitude of overall pitch motion and prolongs the occurrence time of sagging deformation; the larger the wave amplitude, the more significant the high-frequency vibration of the structure caused by it .Conclusions For ships with large openings in the middle, the high-frequency stress generated during sagging is greater than that during hogging, and the superposition of low-frequency stress poses a greater threat to ship safety, which needs to be considered in ship design.This type of ship model can provide reference for the study of plastic collapse of ships in waves.