For the underwater deployment process of heavy-duty deep-sea operational equipment (mining vehicle) from a high freeboard deep-sea mining mother ship, this paper establishes a hydrodynamic simulation method and numerical model that includes the operational mother ship, mining vehicle, and deployment cable. The numerical model is calibrated using tank test data. Potential risk points are identified through numerical simulation, and corresponding solutions are proposed. The study based on the numerical model examines the effects of mining vehicle mass, deployment cable length, and the direction of wind, waves, and currents on the overall system response during the deployment of heavy-duty operational equipment. The analysis reveals the potential risk of moon pool boundary collisions when deploying heavy-duty operational equipment from a high freeboard operational ship. To address this issue, different types of damping devices are designed to suppress the deployment cable motion response. The damping effects of these devices are analyzed through the numerical model, providing recommendations for the safe deployment of the mining vehicle and advice on selecting suitable damping devices.