Abstract: SiC/SiC composites are a key candidate material for hot-section components in aero-engines, but their long-term service relies on environmental barrier coatings (EBCs) to resist high-temperature water-vapor attack and molten calcium-magnesium-aluminosilicate (CMAS) corrosion. Because bare SiC/SiC cannot withstand engine environments over long durations, making the damage and failure mechanisms of these coatings a central scientific issue that governs engine reliability. The core challenge for EBCs lies in their nonlinear degradation and damage accumulation under coupled thermal, mechanical, and chemical fields. Conventional development paradigms based on single-property screening are unable to predict such failure behavior. From the perspective of multi-field coupled mechanics under extreme service environments, this article systematically reviews the complex damage mechanisms of EBCs under near-service conditions and emphasizes an integrated strategy that combines near-service environment simulation experiments with multi-scale mechanical modeling. In particular, this strategy highlights the acquisition of key parameters, such as reaction-layer thickness, interfacial toughness degradation, oxidation growth rate, and residual stress evolution, so that experimental observations can be connected with model-based failure prediction. It elucidates the physicochemical interactions and competing failure mechanisms among thermomechanical damage, water-vapor-induced oxidation and volatilization, and CMAS melt infiltration and spallation. On this basis, the review discusses multiscale thermo-chemo-mechanical modeling approaches involving oxidation-induced growth stress, chemical reaction kinetics, crack propagation driving forces, interfacial delamination, spallation criteria, and damage accumulation. These models provide a basis for linking microstructural damage evolution to macroscopic failure boundaries and engineering life assessment. The study indicates that reliable EBCs design must shift from empirical property selection to a theoretical framework centered on coupled damage modeling. Through iterative coupling between experimental data and model predictions, a comprehensive methodology can be established for engineering life assessment, thereby providing scientific evidence and methodological support for the independent development and long-term service of EBCs for next-generation high-performance aero-engines.