Abstract: To address the operational requirements of offshore UAV swarms, an offshore launch platform suitable for lightweight UAVs is designed in this paper. By establishing kinematics and wave models, the hydrodynamic characteristics are analyzed to achieve attitude stability under Sea State 4. An attitude control device is innovatively designed. Time-domain simulations and scaled-model tank tests are condcuted through OrcaFlex software and the Newmark-β method. It is concluded that the installed attitude control device achieves adaptive stability for the launch platform. Furthermore, an active control strategy is proposed utilizing the moment generated by the rapid rotation of a floating disc, optimizing control performance by adjusting the rotational angular velocity. The results demonstrate that this active control strategy effectively suppresses wave-induced attitude disturbances and significantly enhances platform stability. This verifies the feasibility of the attitude control device for offshore applications and provides a theoretical basis for determining launch windows for payloads on offshore launch platforms.