Enhancing the reliability of nuclear power plant equipment is a crucial method for achieving safe and economical operation. For nuclear power plants, especially the reliability of key equipment, is essential to ensure the safe and stable operation of the plant while effectively improving its economic efficiency. Guided by the “WANO GL 2018-02 Equipment Reliability” document compiled by the WANO Equipment Reliability Group, various nuclear power plants have gradually established a management system for equipment reliability classification. The significant characteristic of high-temperature gas-cooled reactors (HTGRs) is the use of inherent safety and passive systems to enhance the safety and reliability of nuclear power plants. However, the safety characteristics and accident features of HTGRs are significantly different from those of pressurized water reactors (PWRs). The equipment classification in this paper is based on INPO AP-913, and it has been developed by researching the technical methods and practical experiences of equipment classification in domestic and international PWR nuclear power plants, combined with the characteristics of HTGRs. The project team has implemented the equipment classification development in the Phase I project of Jiangsu Xuyu Nuclear Energy Heating Plant (HTGR) and applied the classification results to design optimization, development of maintenance programs, performance monitoring, life management, and maintenance rules.