This paper reviews the research progress and application of key components in the hydrogen fuel cell system, focusing on the hydrogen circulation system. The hydrogen cycle system, which includes hydrogen circulation pumps, ejectors, and steam separators, enhances the efficiency, water capacity, and thermal management of fuel cells, improving system safety. The paper introduces the structure and principles of these components, analyzes their advantages, and reviews the latest research and industrialization status. It discusses technical challenges and future development directions, providing a reference for hydrogen energy storage and application technology in hydrogen fuel cell systems. hydrogen circulation system; hydrogen fuel cell; hydrogen circulation pump; ejector; steam separator The rapid development of the global economy and population has increased the demand for energy, leading to environmental pollution and the greenhouse effect. Hydrogen, with its high calorific value and clean properties, is becoming an important alternative energy source, playing a crucial role in decarbonization efforts. Hydrogen fuel cells are being explored for various applications, including transportation and aviation, due to their high efficiency, zero emissions, and fast start-up capabilities. The hydrogen circulation system, which includes components like hydrogen circulation pumps, ejectors, and steam separators, is essential for improving hydrogen utilization and system performance. The hydrogen circulation system has evolved from direct line circulation and dead-end modes to more efficient recycling patterns. Single hydrogen circulation pump schemes, single-ejector schemes, and multi-purpose schemes using multiple ejectors have been developed to improve hydrogen utilization and system performance. The paper discusses the advantages and limitations of different schemes, such as the single hydrogen circulation pump, single-ejector, and multi-ejector systems, and their impact on system efficiency and cost. Hydrogen circulation pumps, including claw, scroll, vortex, lobe, screw, and Roots-type pumps, have been studied for their performance and efficiency. Each type has unique characteristics, such as durability, compact structure, high efficiency, and low noise. The paper reviews the design, performance, and challenges of these pumps, highlighting the importance of selecting the appropriate pump based on working conditions and environmental requirements. The paper concludes by discussing the future challenges and directions for the development of hydrogen circulation systems, emphasizing the need for further research to address technical challenges and improve system performance. It provides recommendations for future studies and applications, aiming to enhance the efficiency and reliability of hydrogen fuel cell systems.This paper reviews the research progress and application of key components in the hydrogen fuel cell system, focusing on the hydrogen circulation system. The hydrogen cycle system, which includes hydrogen circulation pumps, ejectors, and steam separators, enhances the efficiency, water capacity, and thermal management of fuel cells, improving system safety. The paper introduces the structure and principles of these components, analyzes their advantages, and reviews the latest research and industrialization status. It discusses technical challenges and future development directions, providing a reference for hydrogen energy storage and application technology in hydrogen fuel cell systems. hydrogen circulation system; hydrogen fuel cell; hydrogen circulation pump; ejector; steam separator The rapid development of the global economy and population has increased the demand for energy, leading to environmental pollution and the greenhouse effect. Hydrogen, with its high calorific value and clean properties, is becoming an important alternative energy source, playing a crucial role in decarbonization efforts. Hydrogen fuel cells are being explored for various applications, including transportation and aviation, due to their high efficiency, zero emissions, and fast start-up capabilities. The hydrogen circulation system, which includes components like hydrogen circulation pumps, ejectors, and steam separators, is essential for improving hydrogen utilization and system performance. The hydrogen circulation system has evolved from direct line circulation and dead-end modes to more efficient recycling patterns. Single hydrogen circulation pump schemes, single-ejector schemes, and multi-purpose schemes using multiple ejectors have been developed to improve hydrogen utilization and system performance. The paper discusses the advantages and limitations of different schemes, such as the single hydrogen circulation pump, single-ejector, and multi-ejector systems, and their impact on system efficiency and cost. Hydrogen circulation pumps, including claw, scroll, vortex, lobe, screw, and Roots-type pumps, have been studied for their performance and efficiency. Each type has unique characteristics, such as durability, compact structure, high efficiency, and low noise. The paper reviews the design, performance, and challenges of these pumps, highlighting the importance of selecting the appropriate pump based on working conditions and environmental requirements. The paper concludes by discussing the future challenges and directions for the development of hydrogen circulation systems, emphasizing the need for further research to address technical challenges and improve system performance. It provides recommendations for future studies and applications, aiming to enhance the efficiency and reliability of hydrogen fuel cell systems.