Abstract: According to the nuclear safety regulations of China, the computer codes used in the accident analysis of high temperature gas-cooled reactors (HTGRs) shall be adequately validated. Regarding the code validation, a general process was recommended in a regulatory guide issued by the U.S. Nuclear Regulatory Commission (NRC). In that process, a cornerstone is the establishment of phenomena identification and ranking tables (PIRTs). In this study, the PIRT development history was reviewed and the nine-step PIRT process developed by NRC was described. Additionally, the PIRT application in the HTGR code validation was preliminarily discussed. The PIRT method can guide the code’s development, assessment and application, thus it is a prerequisite step of the HTGR code validation work. Since the nine-step PIRT is a general and advanced process, this process is completely applicable to the HTGR PIRT work of China.