In 2017, the Ministry of Transport issued the R5 version of the CCAR121 Large Aircraft Public Air Transport Carrier Operational Certification Rules. The main changes in the maintenance system exist in Annex J: Continuous Airworthiness and Safety Improvement. Department of Aircraft Airworthiness Certification of Civil Aviation Administration of China also issued or revised 8 corresponding advisory notices. Among them, the “Injury Tolerance Inspection Requirements for AC-121-FS-2018-71 Repair and Modification” is the key one. This paper introduces and expounds the history of “safety life”, “damage safety” and the final development of “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, which could provide reference for the designers and the professional personnel and deepen the understanding of the aircraft structural safety design concept.