Abstract: Rectangular caisson is widely used in the construction of large-span bridge foundations in China, and the construction scheme of sinking is often carried out using anchoring cable positioning system in practical engineering. The sinking construction of offshore caisson often encounters wave action, which causes complex dynamic response on the caisson-positioning system. It will then affect its positioning accuracy, efficiency and even threaten construction safety. In order to study the dynamic response characteristics of the caisson-positioning system under wave action, wave tank experiment was conducted using a rectangular caisson-positioning system for a sea-crossing bridge as the research background. Regarding the commonly encountered in-site wave conditions during construction, the anchoring cable force and displacement response of the caisson for the positioning system during the initial and precise positioning stages under regular and irregular wave action were investigated. The experimental results show that under the action of transverse regular waves, the caisson -positioning system undergoes lateral sway motion mainly caused by the wave induced forced vibration. The horizontal movement trajectory of the caisson exhibits back and forth straight line feature, and the heave motion is not very obvious. The dynamic response characteristics of the positioning system are basically consistent between the two positioning stages. However, greater dynamic response of the caisson-positioning system during the precise positioning stage can be found compared with that of the initial positioning stage. Under the action of transverse irregular waves, the caisson-positioning system not only experiences lateral sway caused by wave forced vibration, but also to some extent was stimulated by an obvious resonance response. Furthermore, the dynamic response characteristics of the systems during two positioning stages are significantly different. Compared with that of transverse regular wave actions, stronger dynamic response and significant differences can be found in the time history feature, frequency spectrum characteristics, response statistics, and motion trajectory of the dynamic response of the caisson-positioning system under irregular wave actions. Compared with the static design value of wave load for fixed structures in the specification, the horizontal wave force obtained from the dynamic response test results of the positioning system under regular wave action is significantly smaller.