In order to fast assess the storage life of the bullet O-ring, the thermal oxidation aging tests of the bullet O-ring were carried with compression permanent distortion as its performance parameter. Based on the experimental test data, regression equation of aging reaction velocity constant and absolute temperature was established. Estimating intervals of reaction velocity constant of the O-ring was provided at 25 degrees Celsius. Aging dynamics equation considering the O-ring compression performance change with time was established, and the safe storage life of the O-ring was 7.4 years. The test results offer reference for determining the replacement cycle of the O-ring. Temperature is the main factor that influences the properties of the rubber sealing ring. The control of the environment temperature should be strengthened in the process of storage.