The thermal decomposition of polymer-bonded explosives （PBX） under complex service environments represents a quintessential multiscale， multiphysics challenge. While progress has been made at individual scales， current research remains fragmented， lacking a cohesive framework that integrates molecular chemistry， mesoscopic damage evolution， and macroscopic thermo-mechanical response. This review systematically synthesizes the state-of-the-art in PBX thermal decomposition， covering methodologies， applications， and critical influencing factors. The key frontiers for future research were identified， including high-spatiotemporal-resolution in situ characterization， multiscale predictive modeling， and decomposition kinetics under confinement. Ultimately， developing physics-based life prediction models is pivotal for accurately assessing munition health and guiding the design of robust， aging-resistant formulations.