Abstract: In frontier fields such as aerospace, transportation, energy, and chemical engineering, brazed joints are widely used in the fabrication and assembly of critical components due to their excellent metallurgical bonding performance, good hermeticity, and adaptability to complex dissimilar materials and special structures. Compared with conventional welding methods, brazing can not only achieve firm bonding at relatively lower temperatures but also effectively reduce damage to base material, thus possessing irreplaceable advantages in complex engineering equipment. However, these brazed joints are often required to serve stably for a long time under extreme environments such as high temperature, high pressure, intense irradiation, or corrosive media. Such environments impose increasingly stringent requirements on their thermal stability, mechanical strength, interfacial reliability, and overall service life. On the basis of systematically sorting out relevant research progress, various potential failure behaviors of brazed joints under complex operating conditions were summarized and analyzed, including creep fracture, interfacial embrittlement, corrosion damage, and irradiation effects, and combined with the limitations of existing technologies, future development directions were proposed, providing a theoretical basis and technical reference for the design of brazed joints with high reliability, the optimization of advanced manufacturing processes, and the establishment of service life prediction models, thereby promoting their wider application in key engineering fields.