Abstract: The cathode of vacuum electronic devices is a key component that determines the overall performance of the tube. M-type cathodes are widely used in various vacuum electronic devices due to their excellent emission performance and high stability. Its reliability and influencing factors are hot topics of concern for both producers and users. This article addresses the deficiencies in current cathode failure mechanism models and the disconnect between accelerated life models and failure mechanisms, establishing an M-type cathode thermal failure mechanism model that comprehensively takes into consideration the interdiffusion of cathode surface films and the evaporation of active materials. Based on this, accelerated life experimental simulations of M-type cathodes were conducted, with the effects of operating stress on threshold parameters, cathode surface state evolution, and emission performance degradation analyzed. The synergistic acceleration mechanisms and interactions of temperature and current density acceleration were investigated. The applicability boundaries of the Arrhenius model were discussed. Meanwhile, the current density acceleration characteristics at different temperatures were demonstrated. Finally, the validity of the model was preliminarily verified by comparison between simulation results and experimental data. The relevant results can provide a reference for multi-stress accelerated life tests and life estimation of electron guns and vacuum devices using M-type cathodes.