The High-Temperature gas-cooled Reactor Pebble-bed Module (HTR-PM) 600 MW HTR-PM (HTR-PM600) nuclear power plant represents a significant advancement in nuclear power technology, especially for the pebble-bed–type High- Temperature Gas-cooled Reactor (HTGR). To ensure operational safety and efficiency of HTGRs, the process radiation monitoring system (PRMS) in HTR-PM600 has been designed to monitor various aspects of radiation in process systems within the nuclear power plant. This system is pivotal for detecting normal operating conditions, diagnosing the performance of fuel elements in the core, and preventing or identifying radioactive leaks into or from the process systems and is based on the Arbeitsgemeinschaft Versuchsreaktor (AVR), Modular HTGR plant, 10 MW High- Temperature gas-cooled experimental Reactor (HTR-10), High-Temperature Gas-Cooled Reactor Demonstration Power Plant (HTR-PM), and other pressurized water reactors. The PRMS can be structured into five subsystems, including the primary circuit activity monitoring subsystem, solid fission product sampling subsystem, liquid process radiation monitoring subsystem, radiation monitoring subsystem for radioactive solid wastes processing system, and area airborne radioactivity monitoring subsystem. This paper first introduces the design of the PRMS of HTR-PM600 and then focuses on the development of the PRMS of HTGRs in China. Moreover, the PRMSs of other HTGRs in the world will be discussed. With the review of technology development and comparison with the design in other countries, more useful advice for the future development of the PRMS of HTGRs will be provided. Furthermore, the paper discusses the development history of the PRMS in HTGRs in China, the relationship between the PRMS and source term, and measurement results of the primary circuit activity monitoring system.