The accelerated stress is used to carry out accelerated life test of specimen so as to shorten test time and reduce test cost.In order to solve the problem of invalid acceleration caused by the change of failure mechanism in the accelerated test of sealing gasket,the ignition loss degradation data of flexible graphite composite gaskets under different temperature stress levels were analyzed.The parameters of the power-law degradation equation and the Arrhenius equation were achieved,and the temperature stress level interval in which the failure mechanism of the gasket does not change was obtained according to the activation energy invariable principle,and the ultimate temperature stress level was determined by means of utilizing statistical distribution method.It is revealed that the pseudo-failure data obtained by power law degradation model for samples at 773 K and 823 K obey the Weibull distribution under the condition that the failure threshold is 5% ignition loss,and the shape parameter corresponding to the temperature stress level 773 K is basically consistent with that at the temperature stress level 823 K.Thereby 823 K can be preliminarily determined as the ultimate temperature stress level of the accelerated test of flexible graphite composite gasket based on the relationship between the consistency of accelerated failure mechanism and shape parameter.It lays a foundation for the determination of accelerated test implementation scheme.