A new idea for the development of semi-submersible medical platform is proposed by modular design idea. The numerical simulation of the effect of ward ventilation system is carried out with the help of Computational Fluid Dynamics (CFD) technology and the effects of different schemes of ventilation system are compared. Based on the best design scheme, the hydrodynamic response of the platform in the complex marine environment is further analyzed, focusing on the influence patterns of the platform hydrodynamic performance on the comfort level of personnel. The results show that: when the air inlet and air exhaust are arranged on the same side, the ventilation effect is the best for the sick and wounded; the medical platform is of good hydrodynamic performance, which can meet the stability requirements of medical work.