Abstract: In order to ensure that the helicopter can provide sufficient floating time for people to evacuate after ditching on the water, the floating characteristics should be thoroughly and extensively studied in the design and development stage. In this paper, a helicopter model is taken as the research object, and the model test method is studied for the helicopter with emergency floatation bags. In this research, the stiffness of the emergency floatation bags, the experimental conditions and the wave direction are the key variables. The results show that the helicopter motion response under regular wave conditions shows a typical cyclical change feature. When the emergency floatation bags is made of flexible material, the structure can weaken the wave response of the helicopter to a certain extent, which is beneficial to the helicopter to maintain the stable floating on the wave surface. When the model floats freely on the water surface, the flexible material can also better assist the helicopter to avoid the most unfavorable wave direction- the horizontal wave that is easy to cause helicopter's overturning and turning over. The model test with no constraints called free floating state is more comprehensive and close to the actual situation. In the model test, the above characteristics should be noted to carry out the relevant test design.