The compression mechanical properties of aviation seat cushion is crucial for passenger impact safety assessment. In order to accelerate the dynamic design of seat cushion and reduce research and development cost, compression mechanical performance experiments were conducted at different strain rates for four types of typical seat cushions. A mechanical model was established to calculate the deformation and energy of flotation seat cushion based on the compression mechanical properties of individual non-flotation material and flotation material, and the accuracy and applicability of the model were evaluated based on quasi-static/dynamic experimental results. Moreover, a dynamic design method for flotation aviation seat cushion was further proposed. The results indicate that under quasi-static and dynamic conditions, the established mechanical model can effectively obtain the compressive mechanical characteristics of flotation seat cushion with different proportions; the calculation accuracy of mechanical model is related to the proportion of flotation material and sensitivity, and is less affected by the ultimate compressive load of non-flotation material. The proposed dynamic design method can quickly optimize parameters such as non-flotation material, flotation material, strain rate, proportion of flotation material, and seat cushion thickness, and simplify the design process of flotation aviation seat cushion.