Electro-thermal integrated energy systems have complex operating mechanisms, where the operational states of system components significantly impact both their failure rates and the reserve levels of the electric and thermal subsystems, thereby affecting overall energy supply reliability. The influence of the operating state on the failure probability and the distribution of power and heat reserve capacity is studied, and a two-stage scheduling model considering dynamic energy supply reliability is established. First, considering the variation of failure probability of the energy supply and transmission components under different load rates, a components failure probability model suitable for day-ahead scheduling is established. Second, considering the conversion efficiency of the equivalent heat storage and electro-thermal coupling units, the model of electro-thermal reserve capacity considering the conversion efficiency is established to explore the flexibility capacity of IEHS under failure states. Finally, a two-stage scheduling model of the IEHS considering the reliability of dynamic energy supply is established. By optimizing the day-ahead operational status of generating units, the model improves component reliability while reducing operating costs and controlling system safety risks. Case studies verify the accuracy and effectiveness of the proposed model.