In order to study the relaxation law of the contact stress of sealing gaskets under long-term compression, the thermal-oxidative aging tests of the sealing gasket at different temperatures were carried out. ABAQUS software was used to establish a three-dimensional compression numerical model of the sealing gasket, so as to analyze the stress distribution inside the sealing gasket and predict the ser-vice life of the sealing gasket based on the test data and the time-temperature superposition principle. The research shows that the performance retention rate of the sealing gasket gradually decreases and tends to be stable with increasing aging time, while decreases with increasing aging temperature. With the increase of compression, holes tend to form at both ends of the sealing gasket due to warping, and the greater the compression, the larger the holes. Therefore, on the premise of meeting the waterproof requirements, the appropriate reduction of compression is conducive to improving the waterproof performance of the sealing gasket. The contact stress between the sealing groove and the sealing gasket is overall higher than that between the sealing gaskets. According to the calculations based on the time-temperature superposition principle, the compression of sealing gasket by 9 mm can meets the 100-year waterproof requirement of a certain subway Line 1. The present research is of great significance for improving the operational capacity of a certain subway Line 1.