Polytetrafluoroethylene (PTFE) has the advantages of high chemical stability, wide operating temperature range, excellent lubrication, etc. It is widely used in aerospace, automotive industry and other engineering fields and plays an important role in sealing applications of low-temperature media. However, in practical engineering applications, the design of PTFE O-rings in low-temperature variable-temperature working conditions lacks a reference basis. Based on the sealing structure of low-temperature pressure vessel, this paper establishes a two-dimensional axisymmetric model using the finite element analysis software Abaqus to study the sealing performance of PTFE O-rings in the static sealing system, and analyzes the effects of temperature, compression rate, cold shrinkage on the deformation of the PTFE O-rings, the Mises stresses, and the contact pressure.