In order to further explore the dynamic sealing performance of spring energized seal ring system under ultra-low temperature conditions,the equivalent two-dimensional axisymmetric finite element model of the spring energized seal ring was established.Two typical numerical assembling processes of the seal ring,i.e.,radial-direction and axial-direction assembling were considered.The sealing characteristics of the seal ring under varying medium pressures from normal room temperature to ultra-low temperature were calculated and analyzed with the stable configurations after assembling.According to the numerical simulation results,three optimization strategies,including the geometric structure of jacket,the width of the substrate and the stiffness of the energized spring of the seal ring,were proposed and evaluated.The results show that the friction of sliding shaft is increased with the increase of medium pressure at both ultra-low temperature and room temperature.The friction at ultra-low temperature is greater than that at room temperature due to the increase of the pressure on the shaft caused by the shrinkage of jacket material at ultra-low temperature.However,the deviation of the friction at the two different temperature decreases as the medium pressure increasing.All the three optimization schemes of the spring energized seal ring can reduce the friction on the premise of having little effect on the sealing characteristics,among which the optimization of the energized spring is most effective for the improvement of the characteristic of seal ring.