To achieve the goal of integrated transportation and installation of mono-column composite bucket foundations for offshore wind turbines, an integrated floating platform was developed. Focusing on the early lowering process of this multi-body coupled system, a laboratory-scale model test with a scale ratio of 1∶80 was designed to investigate the dynamic characteristics of the integrated lowering process, including the motion response of the wind turbine and installation platform, compartment air pressure of the composite bucket foundation, and mooring cable tension. The research found that during the lowering process, with the assistance of the auxiliary installation platform for protection, the longitudinal and lateral oscillation responses of the entire wind turbine are well controlled. The extreme values of the longitudinal oscillation angle significantly increases before the top cover of the cylinder was submerged, and then gradually stabilizes after submersion. The mean and fluctuation amplitude of the cabin pressure on the wave-facing side of the cylinder interior significantly increases. The buoyancy stability of the installation platform is better, with the amplitude of the longitudinal and lateral oscillation angles being able to be controlled within 2°. The mooring force on the wave-facing side of the platform is relatively large, and the mean, extreme, and fluctuation amplitudes of the cable tension all show an upward trend. The peak mooring force could reach 302.75 t. The result can provide a theoretical basis and technical support for the integrated installation of wind turbine foundations in practical engineering applications, while offering more guidance for optimizing installation platform design and improving construction efficiency and safety.