Abstract: An overview of the current landscape of international standards for pressure reducing valves was provided, with detailed elaboration on the key testing points specified in ISO 19887-1:2024. A comparative analysis was conducted to identify the differences and complementary aspects between this international standard and the Chinese national standard GB/T 42536—2023. This research offered technical guidance for the design, testing, and certification of pressure reducing valves used in hydrogen fuel cell vehicles, thereby contributing to the standardization and global development of the industry.