In order to improve the maintenance level of unmanned aerial vehicle (UAV) system, failure mode, effects and criticality analysis (FMECA) is carried out for its airborne link system. The composition, structure and function of the whole airborne link system are analyzed, and then the function and structure principle of the airborne link system are analyzed. The airborne link system to be analyzed is divided into two subsystems: airborne satellite communication link and airborne line-of-sight link. The fault criteria of the airborne link system and the two subsystems were defined, and the failure analysis of the two subsystems was carried out according to the system technical specifications and the actual working conditions. Complete the FMECA form of the airborne link system and identify the weak link of the airborne link system. The results show that this study can provide a basis for the subsequent modeling and optimization work based on multi-state dynamic fault tree.