The creep relaxation of gasket during long-term use at high temperature leads to the decrease of gasket stress, which affects the sealing effect. Therefore, it is very important to use the theoretical model to predict the creep relaxation of the gasket and determine the variation law of the leakage rate of the gasket during long-term use at high temperature. The gasket stress values of graphene oxide non-asbestos gaskets at different temperatures and different preloads were tested through experiments and compared with the gasket stress values calculated by Burgers model. Then, by establishing the relationship between the leakage rate and the use time, the leakage rate calculation method for graphene oxide non-asbestos gasket under different temperatures and preloads for long-term use is proposed, and the leakage rate variation with time is calculated. The results show that the stress relaxation of gasket increases with the increase of preload. With the increase of using time, the stress relaxation of gasket becomes more gentle; when the preload load is the same, the higher the temperature, the more obvious the stress drop of the gasket; the predicted gasket stress values of Burgers model are in good agreement with the experimental values, and the maximum error is 4.4728%; when the temperature is constant, the calculated leakage rate of graphene oxide non-asbestos gasket decreases with the increase of preload; when the preload is the same, the leakage rate of gasket increases with the increase of temperature and the leakage rate is less than 2×10-3 mg·s-1·mm-1 of sealing grade T2. The results provide a basis for the sealing performance application of graphene oxide non-asbestos gasket during long-term use at high temperature.