Radar absorbing materials are prone to delamination, peeling, blistering, discoloration, deterioration, corrosion, and other damages in the process of use, resulting in the degradation of stealth performance. It is important to research on damage detection and repair technology of stealth coatings to improve the performance and life of weapons and equipment. Compared with the metal and composite structure damage that only requires a single non-destructive test, the detection of damage to the radar absorbing materials (RAMs) includes both non-destructive testing and reflectivity testing. In this study, we reviewed the main methods currently used for these two testing of the RAMs in service, introduced the progress of related detection technologies globally, discussed the scientific problems still to be solved in the detection of stealth coating damage on military aircraft, and analyzed and predicted the future development of stealth coating damage detection technology for military aircraft.