Abstract: Perfluoro ethylene propylene (FEP) has excellent chemical stability and high and low temperature resistances. It can maintain a good sealing effect in an extreme space environment and protect the precision equipment inside the spacecraft from the influence of external environments. FEP is prone to creep under long-term loading, which leads to the decrease of gasket sealing performance and ultimately leads to sealing failure. In this study, the creep properties of FEP materials were measured by experiments, and the creep constitutive model suitable for FEP materials was determined. The gasket seal analysis model considering the creep of FEP was constructed and the performance of this model was verified by experiments. The structure of gasket seal was optimized by the response surface method (RSM) and particle swarm optimization (PSO). After optimization, the maximum Mises stress and strain of the gasket seal was reduced, and the maximum contact stress was increased. The maximum strain was reduced by 20.94 %, which not only enhanced the sealing ability of the gasket seal, but also significantly improved the anti-deformation ability.