The aircraft auxiliary power unit (APU) is an indispensable component on the main types of modern civil aircraft, while the application of thermal barrier coatings (TBCs) in APU can reduce engine fuel consumption, improve engine efficiency, and extend the service life of hot section components. This article firstly makes an overview of the structure and working principle of the aircraft APU, as well as the material and structure system of the TBCs. Secondly, the article summarizes the preparation technology and application characteristics of TBCs on hot section components of aircraft APU, mainly focusing on two types of TBCs:Air Plasma Spraying (APS) and Electron-Beam Physical Vapor Deposition (EB-PVD). On this basis, the article concludes the typical failure modes of TBCs applied in civil aircraft APU:including high-temperature oxidation failure, ablation failure, CMAS corrosion, particle impact, etc. At the same time, the failure mechanism of the above failure modes are discussed combining with TGO growth, strain energy release, creep and fatigue, particle deposition, foreign object damage and other behaviors. In addition, the failure analyzing means and methods of aircraft APU TBCs are elaborated in detail from the aspects of microstructure observation, fracture mechanics calculation, and finite element modeling. Finally, maintenance suggestions and precautions based on TBCs are given to improve the service life and system reliability of APU according to the actual situation of air companies.