In 2017, the Ministry of Communications issued the R5 version of the CCAR121 Large Aircraft Public Air Transport Carrier Operational Certification Rules. The main changes in the maintenance system are Annex J: Continuous Airworthiness and Safety Improvement. The Civil Aviation Authority Certification Division also issued/revised 8 A corresponding advisory notice. The key regulations are the “Injury Tolerance Inspection Requirements for AC-121-FS-2018-71 Repair and Modification”. This paper introduces and expounds the history of “safety life”, “damage safety” “damage tolerance” in regulations and advisory notices through key accidents in civil aviation history, and partially implements the corresponding provisions of Annex J and advisory circulars. The personnel can provide reference and deepen the understanding of the aircraft structural safety design concept.